Data transmission method, network device, and terminal device

ABSTRACT

The present disclosure relates to data transmission methods, network devices. One example data transmission method includes: a first network node sends a first indication information to a second network node, the first indication information includes information about an uplink data volume of a buffer of a terminal device, or the first indication information indicates a relationship between an uplink data volume of a buffer of a terminal device and a predefined data volume threshold.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.16/584,299, filed on Sep. 26, 2019, which claims priority toInternational Application No. PCT/CN2018/091627, filed on Jun. 15, 2018,which claims priority to Chinese Patent Application No. 201710450223.1,filed on Jun. 15, 2017. All of the aforementioned patent applicationsare hereby incorporated by reference in their entireties.

TECHNICAL FIELD

This application relates to the communications field, and morespecifically, to a data transmission method, a network device, and aterminal device.

BACKGROUND

In a cloud radio access network (Cloud Radio Access Network, CRAN)architecture, separation of a CRAN control node (Central Unit or ControlUnit, CU) from a data unit (Data Unit or Distributed Unit, DU) isintroduced, that is, an overall baseband processing unit (Building BaseBand Unit, BBU) that is originally deployed is divided into two parts. Adifference from an original base station architecture lies in that,because of separation of the CU from the DU, an interface between the CUand the DU is introduced, and information that is originally exchangedin a base station needs to be transferred through the interface betweenthe CU and the DU.

A radio resource control (Radio Resource Control, RRC) connectionestablishment procedure is a necessary procedure when a terminalaccesses a communications network. In a network architecture in which anexisting base station is used as an independent device, for example, ina long term evolution (Long Term Evolution, LTE) system, the basestation supports all protocol layer processing, and the RRC connectionestablishment procedure may be directly processed by the base station.In a 5G system, if a function of the base station is implemented by a DUand a CU, the RRC connection process needs to be processed by the DU andthe CU through interaction. Therefore, a processing method and aninterface transmission method need to be provided when the DU and the CUestablish an RRC connection.

At present, a state switching solution in an architecture including theCU and the DU is not supported, and the CU cannot perceive a bufferstatus report (Buffer Status Report, BSR) reported by a user, that is,can neither perceive a data buffer of a terminal device in time norswitch the terminal device to an active state or perform ahigh-throughput multi-connection configuration in time. When the CUinstructs the terminal device to change a key, the CU can performsecurity processing by using only a new key, and the CU fails to decryptdata that is being sent before a switching command is received and thatis protected by using an old key.

SUMMARY

This application provides a data transmission method, a network device,and a terminal device, so that when some functions of a network deviceare separated and serve as different network nodes, a second networknode can perceive change information of a data volume of a terminaldevice or a service in time, the second network node can perceive, intime, that the terminal device has performed a random access procedure,and the second network node can implicitly perceive that a key of theterminal device has already been changed completely.

According to a first aspect, a data transmission method is provided. Themethod includes: receiving, by a first network node, a first report froma terminal device, where the first report is used to indicate an uplinkdata volume of a buffer of the terminal device; and sending, by thefirst network node, first indication information to a second networknode, where the first indication information includes information aboutthe uplink data volume of the buffer of the terminal device, or thefirst indication information is used to indicate a relationship betweenthe uplink data volume of the buffer of the terminal device and apredefined data volume threshold.

In some possible implementations, the first report is a buffer statusreport BSR.

In some possible implementations, the first report is the information ofthe data volume of the buffer of the terminal device and MAC controlinformation multiplexed by first information, and the first informationmay be a power headroom report.

In some possible implementations, the relationship between the uplinkdata volume of the buffer of the terminal device and the predefined datavolume threshold is that the uplink data volume of the buffer of theterminal device is greater than, less than, or equal to the predefineddata volume threshold.

In some possible implementations, the first indication information isfurther used to instruct the second network node to perform stateswitching or perform offloading configuration of a radio bearer for theterminal device.

In some possible implementations, the uplink data volume of the bufferof the terminal device includes at least one of a data volume of allradio bearers or a specified radio bearer used for uplink transmissionof the terminal device, a data volume of all logical channels or aspecified logical channel used for uplink transmission of the terminaldevice, a data volume of all logical channel groups or a specifiedlogical channel group used for uplink transmission of the terminaldevice, or a data volume of all quality of service flows or a specifiedquality of service flow used for uplink transmission of the terminaldevice.

With reference to the first aspect, in a first possible implementationof the first aspect, the method further includes: receiving, by thefirst network node, second indication information sent by the secondnetwork node, where the second indication information is used toindicate the predefined data volume threshold to the first network node,or the second indication information is used to instruct the firstnetwork node to send the information about the uplink data volume of thebuffer of the terminal device to the second network node; and thesending, by the first network node, first indication information to asecond network node includes: sending, by the first network node, thefirst indication information to the second network node according to thesecond indication information.

In some possible implementations, if the uplink data volume of thebuffer of the terminal device is greater than or equal to the predefineddata volume threshold, the first network node sends the first indicationinformation to the second network node.

With reference to the first aspect or the first possible implementationof the first aspect, in a second possible implementation of the firstaspect, the first network node includes at least one of a function of aradio link layer control protocol layer, a function of a media accesscontrol layer, and a function of a physical layer; and/or the secondnetwork node includes at least one of a function of a packet dataconvergence protocol layer, a function of a service data adaptationlayer, and a radio resource control function.

In some possible implementations, the second indication information isused to instruct the first network node to enable reporting of the firstindication information; and the sending, by the first network node,first indication information to a second network node includes: sending,by the first network node, the first indication information to thesecond network node according to the second indication information.

According to the data transmission method in this embodiment of thisapplication, when some functions of a network device are separated andserve as different network nodes, the network device can perceive changeinformation of a data volume of a terminal device or a service in time.This prevents the terminal device from redesigning a buffer data volumechange notification for the second network node.

According to a second aspect, a data transmission method is provided.The method includes: receiving, by a second network node, a firstindication message sent by a first network node, where the firstindication message is used to indicate information about an uplink datavolume of a buffer of the terminal device to the second network node, orthe first indication information is used to indicate a relationshipbetween an uplink data volume of a buffer of the terminal device and apredefined data volume threshold; and determining, by the second networknode according to the first indication message, whether to perform stateswitching or perform offloading configuration of a radio bearer for theterminal device.

In some possible implementations, the relationship between the uplinkdata volume of the buffer of the terminal device and the predefined datavolume threshold is that the uplink data volume of the buffer of theterminal device is greater than, less than, or equal to the predefineddata volume threshold.

In some possible implementations, the uplink data volume of the bufferof the terminal device includes at least one of a data volume of allradio bearers or a specified radio bearer used for uplink transmissionof the terminal device, a data volume of all logical channels or aspecified logical channel used for uplink transmission of the terminaldevice, a data volume of all logical channel groups or a specifiedlogical channel group used for uplink transmission of the terminaldevice, or a data volume of all quality of service flows or a specifiedquality of service flow used for uplink transmission of the terminaldevice.

With reference to the second aspect, in a first possible implementationof the second aspect, the method further includes: sending, by thesecond network node, second indication information to the first networknode, where the second indication information is used to indicate thepredefined data volume threshold to the first network node, or thesecond indication information is used to instruct the first network nodeto send the information about the uplink data volume of the buffer ofthe terminal device to the second network node.

In some possible implementations, the second indication information isused to instruct the first network node to enable reporting of theinformation about the data volume.

In some possible implementations, the second indication information isused to instruct the first network node to enable reporting of theinformation about the data volume for a specified terminal device, aspecified bearer, or a specified logical channel.

In some possible implementations, the second indication information isfurther used to instruct the first network node to send the firstindication information to the second network node if the uplink datavolume of the buffer of the terminal device is greater than or equal tothe predefined data volume threshold.

With reference to the second aspect or the first possible implementationof the second aspect, in a second possible implementation of the secondaspect, the state switching includes switching from an inactive state toan active state.

With reference to any one of the second aspect or the first and secondpossible implementations of the second aspect, in a third possibleimplementation of the second aspect, the first network node includes atleast one of a function of a radio link layer control protocol layer, afunction of a media access control layer, and a function of a physicallayer; and/or the second network node includes at least one of afunction of a packet data convergence protocol layer, a function of aservice data adaptation layer, and a radio resource control function.

According to a third aspect, a data transmission method is provided. Themethod includes: sending, by a terminal device, a first report to afirst network node, where the first report is used to indicate an uplinkdata volume of a buffer of the terminal device; and receiving, by theterminal device, indication information sent by a second network node,where the indication information is used to determine whether to performstate switching or perform offloading configuration of a radio bearerfor the terminal device.

In some possible implementations, the first report is a buffer statusreport BSR.

In some possible implementations, the first report is the information ofthe data volume of the buffer of the terminal device and MAC controlinformation multiplexed by first information, and the first informationmay be a power headroom report.

In some possible implementations, the first indication information isfurther used to instruct the second network node to perform stateswitching or perform offloading configuration of a radio bearer for theterminal device.

In some possible implementations, the uplink data volume of the bufferof the terminal device includes at least one of a data volume of allradio bearers or a specified radio bearer used for uplink transmissionof the terminal device, a data volume of all logical channels or aspecified logical channel used for uplink transmission of the terminaldevice, a data volume of all logical channel groups or a specifiedlogical channel group used for uplink transmission of the terminaldevice, or a data volume of all quality of service flows or a specifiedquality of service flow used for uplink transmission of the terminaldevice.

With reference to the third aspect, in a first possible implementationof the third aspect, the first network node includes at least one of afunction of a radio link layer control protocol layer, a function of amedia access control layer, and a function of a physical layer; and/orthe second network node includes at least one of a function of a packetdata convergence protocol layer, a function of a service data adaptationlayer, and a radio resource control function.

According to a fourth aspect, a data transmission method is provided.The method includes: receiving, by a first network node, uplink datasent by the terminal, where the first network node includes at least oneof a function of a radio link layer control protocol layer, a functionof a media access control layer, and a function of a physical layer; andsending, by the first network node, third indication information to asecond network node, where the third indication information is used toindicate, to the second network node, that the uplink data is uplinkdata that is sent in a random access procedure or after random access oruplink data that is sent on an uplink grant, and the second network nodeincludes at least one of a function of a packet data convergenceprotocol layer, a function of a service data adaptation layer, and aradio resource control function.

With reference to the fourth aspect, in a first possible implementationof the fourth aspect, before the receiving, by a first network node,uplink data sent by the terminal device, the method further includes:receiving, by the first network node, a random access preamble sequencesent by the terminal device; and sending, by the first network node, arandom access response to the terminal device.

With reference to the fourth aspect, in a second possible implementationof the fourth aspect, the receiving, by a first network node, uplinkdata sent by the terminal includes: receiving, by the first network nodeon the uplink grant, the uplink data sent by the terminal device.

With reference to any one of the fourth aspect or the first and secondpossible implementations of the fourth aspect, in a third possibleimplementation of the fourth aspect, the sending third indicationinformation to a second network node includes: sending, by the firstnetwork node, the third indication information to the second networknode on a dedicated bearer, where the dedicated bearer is a dedicatedbearer between the first network node and the second network node thatcorresponds to the terminal device.

With reference to any one of the fourth aspect or the first and secondpossible implementations of the fourth aspect, in a fourth possibleimplementation of the fourth aspect, the sending third indicationinformation to a second network node includes: sending, by the firstnetwork node, the third indication information to the second networknode on a common channel, where the common channel is a channel betweenthe first network node and the second network node that is used by theterminal device to send the uplink data in the random access procedure.

In some possible implementations, the third indication informationincludes identifier information of the terminal device.

In some possible implementations, the method further includes: sending,by the first network node, the uplink grant configuration parameter tothe terminal device.

In some possible implementations, the method further includes:receiving, by the first network node, an uplink grant configurationparameter request message sent by the second network node; and sending,by the first network node, the uplink grant configuration parameter tothe second network node based on the uplink grant configurationparameter request message.

In some possible implementations, the first network node receives theuplink grant configuration parameter sent by the second network node.

In some possible implementations, the identifier information is a cellradio network temporary identifier or context identifier information ofthe terminal device.

According to the data transmission method in this embodiment of thisapplication, when some functions of a network device are separated andserve as different network nodes, the second network node can perceive,in time, that a terminal device has performed a random access procedure,and the second network node can implicitly perceive that a key of theterminal device has already been changed completely.

According to a fifth aspect, a data transmission method is provided. Themethod includes: receiving, by a first network node, a dedicated randomaccess preamble sequence sent by the terminal, where the first networknode includes at least one of a function of a radio link layer controlprotocol layer, a function of a media access control layer, and afunction of a physical layer; and sending, by the first network node,third indication information to a second network node, where the thirdindication information is used to indicate, to the second network node,that the terminal device has performed a random access procedure, andthe second network node includes at least one of a function of a packetdata convergence protocol layer, a function of a service data adaptationlayer, and a radio resource control function.

With reference to the fifth aspect, in a first possible implementationof the fifth aspect, the sending third indication information to asecond network node includes: sending, by the first network node, thethird indication information to the second network node on a dedicatedbearer, where the dedicated bearer is a dedicated bearer between thefirst network node and the second network node that corresponds to theterminal device.

With reference to the fifth aspect, in a second possible implementationof the fifth aspect, the sending third indication information to asecond network node includes: sending, by the first network node, thethird indication information to the second network node on a commonchannel, where the common channel is a channel between the first networknode and the second network node that is used by the terminal device tosend the uplink data in the random access procedure.

In some possible implementations, the third indication informationincludes identifier information of the terminal device.

In some possible implementations, the method further includes: sending,by the first network node, the dedicated random access preamble sequenceto the terminal device.

In some possible implementations, the method further includes:receiving, by the first network node, a preamble sequence requestmessage sent by the second network node; and sending, by the firstnetwork node, the dedicated random access preamble sequence to thesecond network node based on the preamble sequence request message.

In some possible implementations, the method further includes:receiving, by the first network node, the dedicated random accesspreamble sequence sent by the second network node.

In some possible implementations, the identifier information is a cellradio network temporary identifier or context identifier information ofthe terminal device.

According to the data transmission method in this embodiment of thisapplication, when some functions of a network device are separated andserve as different network nodes, the second network node can perceive,in time, that a terminal device has performed a random access procedure,and the second network node can implicitly perceive that a key of theterminal device has already been changed completely.

According to a sixth aspect, a data transmission method is provided. Themethod includes: sending, by a second network node, a first message,where the first message is used to instruct a terminal device to changea key, and the second network node includes at least one of a functionof a packet data convergence protocol layer, a function of a servicedata adaptation layer, and a radio resource control function; andreceiving, by the second network node, third indication information sentby a first network node, where the third indication information is usedto indicate, to the second network node, that uplink data received bythe first network node is uplink data that is sent in a random accessprocedure or after a random access procedure or uplink data that is senton an uplink grant, or the third indication information is used toindicate, to the second network node, that the terminal device hasperformed a random access procedure, and the first network node includesat least one of a function of a radio link layer control protocol layer,a function of a media access control layer, and a function of a physicallayer.

In some possible implementations, the first message includes a dedicatedrandom access preamble sequence of the terminal device or an uplinkgrant configuration parameter used to send data.

With reference to the sixth aspect, in a first possible implementationof the sixth aspect, the receiving, by the second network node, thirdindication information sent by the first network node includes:receiving, by the second network node on a dedicated bearer, the thirdindication information sent by the second network node, where thededicated bearer is a dedicated bearer between the first network nodeand the second network node that corresponds to the terminal device.

With reference to the sixth aspect, in a second possible implementationof the sixth aspect, the receiving, by the second network node, thirdindication information sent by the first network node includes:receiving, by the second network node on a common channel, the thirdindication information sent by the second network node, where the commonchannel is a channel between the first network node and the secondnetwork node that is used by the terminal device to send the uplink datain the random access procedure.

In some possible implementations, the third indication informationincludes the dedicated random access preamble sequence of the terminaldevice or identifier information of the terminal device.

In some possible implementations, the method further includes: sending,by the second network node, a preamble sequence request message or anuplink grant configuration parameter request message to the firstnetwork node; and receiving, by the second network node, the dedicatedrandom access preamble sequence sent by the first network node or anuplink grant configuration parameter used to send data.

In some possible implementations, the second network node sends, to thefirst network node, the dedicated random access preamble sequence or theuplink grant configuration parameter used to send data.

In some possible implementations, the identifier information is a cellradio network temporary identifier or context identifier information ofthe terminal device.

According to a seventh aspect, a data transmission method is provided.The method includes: receiving, by a terminal device, a first messagefrom a second network node, where the first message is used to instructthe terminal device to change a key, and the second network nodeincludes at least one of a function of a packet data convergenceprotocol layer, a function of a service data adaptation layer, and aradio resource control function; and sending, by the terminal device,uplink data to a first network node, where the first network nodeincludes at least one of a function of a radio link layer controlprotocol layer, a function of a media access control layer, and afunction of a physical layer.

With reference to the seventh aspect, in a first possible implementationof the seventh aspect, before the sending, by the terminal device,uplink data to a first network node, the method further includes:sending, by the terminal device, a random access preamble sequence tothe first network node; and receiving, by the terminal device, a randomaccess response sent by the first network node.

With reference to the seventh aspect, in a second possibleimplementation of the seventh aspect, before the sending, by theterminal device, uplink data to a first network node, the method furtherincludes: receiving, by the terminal device, an uplink grantconfiguration parameter; and the sending, by the terminal device, uplinkdata to a first network node includes: sending, by the terminal device,the uplink data to the first network node on an uplink grant.

In some possible implementations, the first message includes the uplinkgrant configuration parameter of the terminal device.

In some possible implementations, the uplink data includes identifierinformation of the terminal device.

In some possible implementations, the identifier information is a cellradio network temporary identifier or context identifier information ofthe terminal device.

In some possible implementations, the method further includes:receiving, by the terminal device, the uplink grant configurationparameter sent by the first network node.

According to an eighth aspect, a data transmission method is provided.The method includes: receiving, by a terminal device, a first messagefrom a second network node, where the first message is used to instructthe terminal device to change a key, and the second network nodeincludes at least one of a function of a packet data convergenceprotocol layer, a function of a service data adaptation layer, and aradio resource control function; and sending, by the terminal device, adedicated random access preamble sequence of the terminal device to afirst network node, where the first network node includes at least oneof a function of a radio link layer control protocol layer, a functionof a media access control layer, and a function of a physical layer.

With reference to the eighth aspect, in a first possible implementationof the eighth aspect, the first message includes the dedicated randomaccess preamble sequence of the terminal device.

With reference to the eighth aspect, in a second possible implementationof the eighth aspect, the method further includes: receiving, by theterminal device, the dedicated random access preamble sequence of theterminal device sent by the first network node.

According to a ninth aspect, a data transmission method is provided. Themethod includes: when there is first data in a buffer of a terminaldevice or a data volume of first data exceeds a predefined data volumethreshold or a discard timer of first data expires within a predefinedtime length, triggering, by the terminal device, a second report, wherethe second report is used to indicate that the first data in the bufferof the terminal device needs to be sent.

In some possible implementations, the first data is data considered tobe relatively important on a bearer. For example, an I frame or abidirectional P frame in video frames is data more important than aunidirectional P frame. It is not excluded that definition of importancemay be agreed on by an operator or an application provider and a user.This is not limited herein.

With reference to the ninth aspect, in a first possible implementationof the ninth aspect, before the triggering, by the terminal device, asecond report, the method further includes: receiving, by the terminaldevice, fourth indication information sent by a third network node,where the fourth indication information is used to instruct the terminaldevice to trigger the data report on a specified logical channel orbearer.

With reference to the first possible implementation of the ninth aspect,in a second possible implementation of the ninth aspect, the thirdnetwork node includes at least one of a function of a radio resourcecontrol protocol layer, a function of a packet data convergence protocollayer, a function of a radio link layer control protocol layer, afunction of a media access control layer, and a function of a physicallayer.

According to the data transmission method in this embodiment of thisapplication, when there is important data in the buffer of the terminaldevice, a network device can be notified in time.

According to a tenth aspect, a data transmission method is provided. Themethod includes: sending, by a third network node, fourth indicationinformation to a terminal device, where the fourth indicationinformation is used to instruct the terminal device to trigger a secondreport on a specified logical channel or bearer, and the second reportis used to indicate that the first data in a buffer of the terminaldevice needs to be sent; and receiving, by the third network node, thesecond report on the specified logical channel or bearer.

In some possible implementations, the third network node includes atleast one of a function of a radio link layer control protocol layer, afunction of a media access control layer, and a function of a physicallayer.

In some possible implementations, the first data is data considered tobe relatively important on a bearer. For example, an I frame or abidirectional P frame in video frames is data more important than aunidirectional P frame. It is not excluded that definition of importancemay be agreed on by an operator or an application provider and a user.This is not limited herein.

According to an eleventh aspect, a network device is provided. Thenetwork device includes: a transceiver module, configured to receive afirst report from a terminal device, where the first report is used toindicate information about an uplink data volume of a buffer of theterminal device; and a processing module, configured to generate firstindication information, where the first indication information includesthe uplink data volume of the buffer of the terminal device, or thefirst indication information is used to indicate a relationship betweenthe uplink data volume of the buffer of the terminal device and apredefined data volume threshold, where the transceiver module isfurther configured to send the first indication information to a secondnetwork node.

In some possible implementations, the first report is a buffer statusreport BSR.

In some possible implementations, the first report is the information ofthe data volume of the buffer of the terminal device and MAC controlinformation multiplexed by first information, and the first informationmay be a power headroom report.

In some possible implementations, the first indication information isfurther used to instruct the second network node to perform stateswitching or perform offloading configuration of a radio bearer for theterminal device.

In some possible implementations, the relationship between the uplinkdata volume of the buffer of the terminal device and the predefined datavolume threshold is that the uplink data volume of the buffer of theterminal device is greater than, less than, or equal to the predefineddata volume threshold.

In some possible implementations, the uplink data volume of the bufferof the terminal device includes at least one of a data volume of allradio bearers or a specified radio bearer used for uplink transmissionof the terminal device, a data volume of all logical channels or aspecified logical channel used for uplink transmission of the terminaldevice, a data volume of all logical channel groups or a specifiedlogical channel group used for uplink transmission of the terminaldevice, or a data volume of all quality of service flows or a specifiedquality of service flow used for uplink transmission of the terminaldevice.

With reference to the eleventh aspect, in a first possibleimplementation of the eleventh aspect, the transceiver module is furtherconfigured to receive second indication information sent by the secondnetwork node, where the second indication information is used toindicate the predefined data volume threshold to the first network node,or the second indication information is used to instruct the firstnetwork node to send the information about the uplink data volume of thebuffer of the terminal device to the second network node; and thetransceiver module is specifically configured to send the firstindication information to the second network node according to thesecond indication information.

In some possible implementations, if the uplink data volume of thebuffer of the terminal device is greater than or equal to the predefineddata volume threshold, the transceiver module is further configured tosend the first indication information to the second network node.

In some possible implementations, the second indication information isused to instruct the first network node to enable reporting of the firstindication information; and the transceiver module is specificallyconfigured to send the first indication information to the secondnetwork node according to the second indication information.

With reference to the eleventh aspect or the first possibleimplementation of the eleventh aspect, in a second possibleimplementation of the eleventh aspect, the network device includes atleast one of a function of a radio link layer control protocol layer, afunction of a media access control layer, and a function of a physicallayer; and/or the second network node includes at least one of afunction of a packet data convergence protocol layer, a function of aservice data adaptation layer, and a radio resource control function.

When some functions of the network device in this embodiment of thisapplication are separated and serve as different network nodes, thenetwork device can perceive change information of a data volume of aterminal device or a service in time. This prevents the terminal devicefrom redesigning a buffer data volume change notification for the secondnetwork node.

According to a twelfth aspect, a network device is provided. The networkdevice includes: a transceiver module, configured to receive a firstindication message sent by a first network node, where the firstindication message is used to indicate information about an uplink datavolume of a buffer of the terminal device to the second network node, orthe first indication information is used to indicate a relationshipbetween an uplink data volume of a buffer of the terminal device and apredefined data volume threshold; and a processing module, configured todetermine, according to the first indication message, whether to performstate switching or perform offloading configuration of a radio bearerfor the terminal device.

In some possible implementations, the relationship between the uplinkdata volume of the buffer of the terminal device and the predefined datavolume threshold is that the uplink data volume of the buffer of theterminal device is greater than, less than, or equal to the predefineddata volume threshold.

In some possible implementations, the uplink data volume of the bufferof the terminal device includes at least one of a data volume of allradio bearers or a specified radio bearer used for uplink transmissionof the terminal device, a data volume of all logical channels or aspecified logical channel used for uplink transmission of the terminaldevice, a data volume of all logical channel groups or a specifiedlogical channel group used for uplink transmission of the terminaldevice, or a data volume of all quality of service flows or a specifiedquality of service flow used for uplink transmission of the terminaldevice.

With reference to the twelfth aspect, in a first possible implementationof the twelfth aspect, the transceiver module is further configured tosend second indication information to the first network node, where thesecond indication information is used to indicate the predefined datavolume threshold to the first network node, or the second indicationinformation is used to instruct the first network node to send theinformation about the uplink data volume of the buffer of the terminaldevice to the second network node.

In some possible implementations, the second indication information isfurther used to instruct the first network node to send the firstindication information to the second network node if the uplink datavolume of the buffer of the terminal device is greater than or equal tothe predefined data volume threshold.

With reference to the twelfth aspect or the first possibleimplementation of the twelfth aspect, in a second possibleimplementation of the twelfth aspect, the state switching includesswitching from an inactive state to an active state.

With reference to any one of the twelfth aspect or the first and secondpossible implementations of the twelfth aspect, in a third possibleimplementation of the twelfth aspect, the first network node includes atleast one of a function of a radio link layer control protocol layer, afunction of a media access control layer, and a function of a physicallayer; and/or the network device includes at least one of a function ofa packet data convergence protocol layer, a function of a service dataadaptation layer, and a radio resource control function.

In some possible implementations, the second indication information isused to instruct the first network node to enable reporting of theinformation about the data volume.

In some possible implementations, the second indication information isused to instruct the first network node to enable reporting of theinformation about the data volume for a specified terminal device, aspecified bearer, or a specified logical channel.

According to a thirteenth aspect, a terminal device is provided. Theterminal device includes: a processing module, configured to generate afirst report, where the first report is used to indicate an uplink datavolume of a buffer of the terminal device; and a transceiver module,configured to send the first report to a first network node, where thetransceiver module is further configured to receive indicationinformation sent by a second network node, where the indicationinformation is used to determine whether to perform state switching orperform offloading configuration of a radio bearer for the terminaldevice.

In some possible implementations, the first report is a buffer statusreport BSR.

In some possible implementations, the first report is the information ofthe data volume of the buffer of the terminal device and MAC controlinformation multiplexed by first information, and the first informationmay be a power headroom report.

In some possible implementations, the uplink data volume of the bufferof the terminal device includes at least one of a data volume of allradio bearers or a specified radio bearer used for uplink transmissionof the terminal device, a data volume of all logical channels or aspecified logical channel used for uplink transmission of the terminaldevice, a data volume of all logical channel groups or a specifiedlogical channel group used for uplink transmission of the terminaldevice, or a data volume of all quality of service flows or a specifiedquality of service flow used for uplink transmission of the terminaldevice.

With reference to the thirteenth aspect, in a first possibleimplementation of the thirteenth aspect, the first network node includesat least one of a function of a radio link layer control protocol layer,a function of a media access control layer, and a function of a physicallayer; and/or the second network node includes at least one of afunction of a packet data convergence protocol layer, a function of aservice data adaptation layer, and a radio resource control function.

According to a fourteenth aspect, a network device is provided. Thenetwork device includes: a transceiver module, configured to receiveuplink data sent by a terminal, where the network device includes atleast one of a function of a radio link layer control protocol layer, afunction of a media access control layer, and a function of a physicallayer; and a processing module, configured to generate third indicationinformation, where the third indication information is used to indicate,to the second network node, that the uplink data is uplink data that issent in a random access procedure or after random access, where thetransceiver module is further configured to send the third indicationinformation to the second network node, where the second network nodeincludes at least one of a function of a packet data convergenceprotocol layer, a function of a service data adaptation layer, and aradio resource control function.

With reference to the fourteenth aspect, in a first possibleimplementation of the fourteenth aspect, the transceiver module isfurther configured to: receive a random access preamble sequence sent bythe terminal device; and send a random access response to the terminaldevice.

With reference to the fourteenth aspect, in a second possibleimplementation of the fourteenth aspect, the transceiver module isspecifically configured to receive, on the uplink grant, the uplink datasent by the terminal device.

With reference to any one of the fourteenth aspect or the first andsecond possible implementations of the fourteenth aspect, in a thirdpossible implementation of the twelfth aspect, the transceiver module isspecifically configured to send the third indication information to thesecond network node on a dedicated bearer, where the dedicated bearer isa dedicated bearer between the first network node and the second networknode that corresponds to the terminal device.

With reference to any one of the fourteenth aspect or the first andsecond possible implementations of the fourteenth aspect, in a fourthpossible implementation of the twelfth aspect, the transceiver module isspecifically configured to send the third indication information to thesecond network node on a common channel, where the common channel is achannel between the first network node and the second network node thatis used by the terminal device to send the uplink data in the randomaccess procedure.

In some possible implementations, the third indication informationincludes identifier information of the terminal device.

In some possible implementations, the transceiver module is furtherconfigured to send an uplink grant configuration parameter of theterminal device to the terminal device.

In some possible implementations, the transceiver module is furtherconfigured to receive an uplink grant configuration parameter requestmessage sent by the second network node; and the processing module isfurther configured to control, based on the uplink grant configurationparameter request message, the transceiver module to send the uplinkgrant configuration parameter to the second network node.

In some possible implementations, the transceiver module is furtherconfigured to receive the uplink grant configuration parameter sent bythe second network node.

In some possible implementations, the identifier information is a cellradio network temporary identifier or context identifier information ofthe terminal device.

According to the network device in this embodiment of this application,when some functions of the network device are separated and serve asdifferent network nodes, the second network node can perceive, in time,that a terminal device has performed a random access procedure, and thesecond network node can implicitly perceive that a key of the terminaldevice has already been changed completely.

According to a fifteenth aspect, a network device is provided. Thenetwork device includes: a transceiver module, configured to receive adedicated random access preamble sequence sent by the terminal, wherethe network device includes at least one of a function of a radio linklayer control protocol layer, a function of a media access controllayer, and a function of a physical layer; and a processing module,configured to generate third indication information, where thetransceiver module is further configured to send third indicationinformation to a second network node, where the third indicationinformation is used to indicate, to the second network node, that theterminal device has performed a random access procedure, and the secondnetwork node includes at least one of a function of a packet dataconvergence protocol layer, a function of a service data adaptationlayer, and a radio resource control function.

With reference to the fifteenth aspect, in a first possibleimplementation of the fifteenth aspect, the transceiver module isspecifically configured to send the third indication information to thesecond network node on a dedicated bearer, where the dedicated bearer isa dedicated bearer between the first network node and the second networknode that corresponds to the terminal device.

With reference to the fifteenth aspect, in a second possibleimplementation of the fifteenth aspect, the transceiver module isspecifically configured to send the third indication information to thesecond network node on a common channel, where the common channel is achannel between the first network node and the second network node thatis used by the terminal device to send the uplink data in the randomaccess procedure.

In some possible implementations, the third indication informationincludes identifier information of the terminal device.

In some possible implementations, the transceiver module is furtherconfigured to send the dedicated random access preamble sequence to theterminal device.

In some possible implementations, the transceiver module is furtherconfigured to receive a preamble sequence request message sent by thesecond network node; and the processing module is further configured tocontrol, based on the preamble sequence request message, the transceivermodule to send the dedicated random access preamble sequence to thesecond network node.

In some possible implementations, the transceiver module is furtherconfigured to receive the dedicated random access preamble sequence sentby the second network node.

In some possible implementations, the identifier information is a cellradio network temporary identifier or context identifier information ofthe terminal device.

According to the network device in this embodiment of this application,when some functions of the network device are separated and serve asdifferent network nodes, the second network node can perceive, in time,that a terminal device has performed a random access procedure, and thesecond network node can implicitly perceive that a key of the terminaldevice has already been changed completely.

According to a sixteenth aspect, a network device is provided. Thenetwork device includes: a processing module, configured to generate afirst message, where the first message is used to instruct a terminaldevice to change a key; and a transceiver module, configured to send thefirst message, where the network device includes at least one of afunction of a packet data convergence protocol layer, a function of aservice data adaptation layer, and a radio resource control function,where the transceiver module is further configured to receive thirdindication information sent by the first network node, where the thirdindication information is used to indicate, to the second network node,that uplink data received by the first network node is uplink data thatis sent in a random access procedure or after a random access procedure,or the third indication information is used to indicate, to the secondnetwork node, that the terminal device has performed a random accessprocedure, where the first network node includes at least one of afunction of a radio link layer control protocol layer, a function of amedia access control layer, and a function of a physical layer.

In some possible implementations, the first message includes a dedicatedrandom access preamble sequence of the terminal device or an uplinkgrant configuration parameter used to send data.

With reference to the sixteenth aspect, in a first possibleimplementation of the sixteenth aspect, the transceiver module isspecifically configured to receive, on a dedicated bearer, the thirdindication information sent by the second network node, where thededicated bearer is a dedicated bearer between the first network nodeand the second network node that corresponds to the terminal device.

With reference to the sixteenth aspect, in a second possibleimplementation of the sixteenth aspect, the transceiver module isspecifically configured to receive, on a common channel, the thirdindication information sent by the second network node, where the commonchannel is a channel between the first network node and the secondnetwork node that is used by the terminal device to send the uplink datain the random access procedure.

In some possible implementations, the third indication informationincludes the dedicated random access preamble sequence of the terminaldevice or identifier information of the terminal device.

In some possible implementations, the transceiver module is furtherconfigured to send a preamble sequence request message or an uplinkgrant configuration parameter request message to the first network node;and the second network node receives the dedicated random accesspreamble sequence sent by the first network node or an uplink grantconfiguration parameter used to send data.

In some possible implementations, the transceiver module is furtherconfigured to send, to the first network node, the dedicated randomaccess preamble sequence or the uplink grant configuration parameterused to send data.

In some possible implementations, the identifier information is a cellradio network temporary identifier or context identifier information ofthe terminal device.

According to a seventeenth aspect, a terminal device is provided. Theterminal device includes: a transceiver module, configured to receive afirst message from a second network node, where the first message isused to instruct the terminal device to change a key, and the secondnetwork node includes at least one of a function of a packet dataconvergence protocol layer, a function of a service data adaptationlayer, and a radio resource control function; and a processing module,configured to control the transceiver module to be further configured tosend uplink data to a first network node, where the first network nodeincludes at least one of a function of a radio link layer controlprotocol layer, a function of a media access control layer, and afunction of a physical layer.

With reference to the seventeenth aspect, in a first possibleimplementation of the seventeenth aspect, the transceiver module isfurther configured to: send a random access preamble sequence to thefirst network node; and receive a random access response sent by thefirst network node.

With reference to the seventeenth aspect, in a second possibleimplementation of the seventeenth aspect, the transceiver module isfurther configured to receive an uplink grant configuration parameter;and the transceiver module is specifically configured to send the uplinkdata to the first network node on an uplink grant.

In some possible implementations, the first message includes the uplinkgrant configuration parameter of the terminal device.

In some possible implementations, the uplink data includes identifierinformation of the terminal device.

In some possible implementations, the identifier information is a cellradio network temporary identifier or context identifier information ofthe terminal device.

In some possible implementations, the transceiver module is furtherconfigured to receive the dedicated random access preamble sequence sentby the first network node or an uplink grant configuration parameterused to send data.

According to an eighteenth aspect, a terminal device is provided. Theterminal device includes: a transceiver module, configured to receive afirst message from a second network node, where the first message isused to instruct the terminal device to change a key, and the secondnetwork node includes at least one of a function of a packet dataconvergence protocol layer, a function of a service data adaptationlayer, and a radio resource control function; and a processing module,configured to control the transceiver module to be further configured tosend a dedicated random access preamble sequence of the terminal deviceto a first network node, where the first network node includes at leastone of a function of a radio link layer control protocol layer, afunction of a media access control layer, and a function of a physicallayer.

With reference to the eighteenth aspect, in a first possibleimplementation of the eighteenth aspect, the first message includes thededicated random access preamble sequence of the terminal device.

With reference to the eighteenth aspect, in a second possibleimplementation of the eighteenth aspect, the transceiver module isfurther configured to receive the dedicated random access preamblesequence of the terminal device sent by the first network node.

According to a nineteenth aspect, a terminal device is provided. Theterminal device includes: a processing module, configured to determinethat there is first data in a buffer of the terminal device or a datavolume of first data exceeds a predefined data volume threshold or adiscard timer of first data expires within a predefined time length; anda transceiver module, configured to trigger a second report, where thesecond report is used to indicate that the first data in the buffer ofthe terminal device needs to be sent.

With reference to the nineteenth aspect, in a first possibleimplementation of the nineteenth aspect, the transceiver module isfurther configured to receive fourth indication information sent by athird network node, where the fourth indication information is used toinstruct the terminal device to send the data report on a specifiedlogical channel or bearer.

With reference to the first possible implementation of the nineteenthaspect, in a second possible implementation of the nineteenth aspect,the third network node includes at least one of a function of a radioresource control protocol layer, a function of a packet data convergenceprotocol layer, a function of a radio link layer control protocol layer,a function of a media access control layer, and a function of a physicallayer.

In some possible implementations, the first data is data considered tobe relatively important on a bearer. For example, an I frame or abidirectional P frame in video frames is data more important than aunidirectional P frame. It is not excluded that definition of importancemay be agreed on by an operator or an application provider and a user.This is not limited herein.

According to a twentieth aspect, a network device is provided. Thenetwork device includes: a processing module, configured to generatefourth indication information, where the fourth indication informationis used to instruct the terminal device to trigger a second report on aspecified logical channel or bearer, and the second report is used toindicate that the first data in a buffer of the terminal device needs tobe sent, and a transceiver module, configured to send fourth indicationinformation to the terminal device, where the transceiver module isfurther configured to receive the second report on the specified logicalchannel or bearer.

In some possible implementations, the third network node includes atleast one of a function of a radio resource control protocol layer, afunction of a packet data convergence protocol layer, a function of aradio link layer control protocol layer, a function of a media accesscontrol layer, and a function of a physical layer.

In some possible implementations, the first data is data considered tobe relatively important on a bearer. For example, an I frame or abidirectional P frame in video frames is data more important than aunidirectional P frame. It is not excluded that definition of importancemay be agreed on by an operator or an application provider and a user.This is not limited herein.

According to a twenty-first aspect, a network device is provided. Thenetwork device includes a memory and a processor, where the memory isconfigured to store an instruction, and the processor is configured toinvoke the instruction in the memory, to perform an operation in themethod according to any one of the first aspect or the possibleimplementations of the first aspect.

According to a twenty-second aspect, a network device is provided. Thenetwork device includes a memory and a processor, where the memory isconfigured to store an instruction, and the processor is configured toinvoke the instruction in the memory, to perform an operation in themethod according to any one of the second aspect or the possibleimplementations of the second aspect.

According to a twenty-third aspect, a terminal device is provided. Theterminal device includes a memory and a processor, where the memory isconfigured to store an instruction, and the processor is configured toinvoke the instruction in the memory, to perform an operation in themethod according to any one of the third aspect or the possibleimplementations of the third aspect.

According to a twenty-fourth aspect, a network device is provided. Thenetwork device includes a memory and a processor, where the memory isconfigured to store an instruction, and the processor is configured toinvoke the instruction in the memory, to perform an operation in themethod according to any one of the fourth aspect or the possibleimplementations of the fourth aspect.

According to a twenty-fifth aspect, a network device is provided. Thenetwork device includes a memory and a processor, where the memory isconfigured to store an instruction, and the processor is configured toinvoke the instruction in the memory, to perform an operation in themethod according to any one of the fifth aspect or the possibleimplementations of the fifth aspect.

According to a twenty-sixth aspect, a network device is provided. Thenetwork device includes a memory and a processor, where the memory isconfigured to store an instruction, and the processor is configured toinvoke the instruction in the memory, to perform an operation in themethod according to any one of the sixth aspect or the possibleimplementations of the sixth aspect.

According to a twenty-seventh aspect, a terminal device is provided. Theterminal device includes a memory and a processor, where the memory isconfigured to store an instruction, and the processor is configured toinvoke the instruction in the memory, to perform an operation in themethod according to any one of the seventh aspect or the possibleimplementations of the seventh aspect.

According to a twenty-eighth aspect, a terminal device is provided. Theterminal device includes a memory and a processor, where the memory isconfigured to store an instruction, and the processor is configured toinvoke the instruction in the memory, to perform an operation in themethod according to any one of the eighth aspect or the possibleimplementations of the eighth aspect.

According to a twenty-ninth aspect, a terminal device is provided. Theterminal device includes a memory and a processor, where the memory isconfigured to store an instruction, and the processor is configured toinvoke the instruction in the memory, to perform an operation in themethod according to any one of the ninth aspect or the possibleimplementations of the ninth aspect.

According to a thirtieth aspect, a network device is provided. Thenetwork device includes a memory and a processor, where the memory isconfigured to store an instruction, and the processor is configured toinvoke the instruction in the memory, to perform an operation in themethod according to any one of the tenth aspect or the possibleimplementations of the tenth aspect.

According to a thirty-first aspect, a computer-readable storage mediumis provided. The computer-readable storage medium stores an instruction,where when the instruction is run on a computer, the computer is enabledto perform the methods according to the foregoing aspects.

According to a thirty-second aspect, a system chip is provided. Thesystem chip includes an input/output interface, at least one processor,at least one memory, and a bus, where the at least one memory isconfigured to store an instruction, and the at least one processor isconfigured to invoke the instruction in the at least one memory, toperform operations in the methods according to the foregoing aspects.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic diagram of an application scenario of a technicalsolution according to an embodiment of this application;

FIG. 2 is a schematic diagram of another application scenario of atechnical solution according to an embodiment of this application;

FIG. 3 is a schematic flowchart of a data transmission method accordingto an embodiment of this application;

FIG. 4 is another schematic flowchart of a data transmission methodaccording to an embodiment of this application;

FIG. 5 is still another schematic flowchart of a data transmissionmethod according to an embodiment of this application;

FIG. 6 is still another schematic flowchart of a data transmissionmethod according to an embodiment of this application;

FIG. 7 is still another schematic flowchart of a data transmissionmethod according to an embodiment of this application;

FIG. 8 is a schematic block diagram of a network device according to anembodiment of this application;

FIG. 9 is another schematic block diagram of a network device accordingto an embodiment of this application;

FIG. 10 is a schematic block diagram of a terminal device according toan embodiment of this application;

FIG. 11 is still another schematic block diagram of a network deviceaccording to an embodiment of this application;

FIG. 12 is still another schematic block diagram of a network deviceaccording to an embodiment of this application;

FIG. 13 is still another schematic block diagram of a network deviceaccording to an embodiment of this application;

FIG. 14 is another schematic block diagram of a terminal deviceaccording to an embodiment of this application;

FIG. 15 is still another schematic block diagram of a terminal deviceaccording to an embodiment of this application;

FIG. 16 is still another schematic block diagram of a terminal deviceaccording to an embodiment of this application;

FIG. 17 is still another schematic block diagram of a network deviceaccording to an embodiment of this application;

FIG. 18 is still another schematic block diagram of a network deviceaccording to an embodiment of this application;

FIG. 19 is still another schematic block diagram of a network deviceaccording to an embodiment of this application;

FIG. 20 is still another schematic block diagram of a terminal deviceaccording to an embodiment of this application;

FIG. 21 is still another schematic block diagram of a network deviceaccording to an embodiment of this application;

FIG. 22 is still another schematic block diagram of a network deviceaccording to an embodiment of this application;

FIG. 23 is still another schematic block diagram of a network deviceaccording to an embodiment of this application;

FIG. 24 is still another schematic block diagram of a terminal deviceaccording to an embodiment of this application:

FIG. 25 is still another schematic block diagram of a terminal deviceaccording to an embodiment of this application;

FIG. 26 is still another schematic block diagram of a terminal deviceaccording to an embodiment of this application; and

FIG. 27 is still another schematic block diagram of a network deviceaccording to an embodiment of this application.

DESCRIPTION OF EMBODIMENTS

The following describes the technical solutions in this application withreference to the accompanying drawings.

The embodiments of this application are applicable to various forms ofsystems including some separated functions of a network device. FIG. 1is a schematic diagram of an application scenario of a technicalsolution according to an embodiment of this application. As shown inFIG. 1 , some functions of the network device are separated and serve asa first network node and a second network node.

Specifically, FIG. 2 is a schematic diagram of another applicationscenario of a technical solution according to an embodiment of thisapplication. As shown in FIG. 2 , in a CRAN architecture, separation ofa CU from a DU is introduced, the DU may correspond to the first networknode in FIG. 1 , and the CU corresponds to the second network node inFIG. 1 .

It should be understood that, the first network node and the secondnetwork node may be two physically or logically separated modules in anoverall network architecture, or may be two logical network elementsthat are completely independent.

The CU has a radio resource control (Radio Resource Control, RRC)function or a partial RRC control function, and includes functions ofall protocol layers of an existing base station or functions of someprotocol layers, for example, includes only the RRC function or thepartial RRC function, or includes the RRC function or a function of aservice data adaptation protocol (Service Data Adaptation Protocol,SDAP) layer, or includes a function of an RRC/packet data convergenceprotocol (Packet Data Convergence Protocol, PDCP) layer, or includes afunction of an RRC/PDCP layer and a partial function of a radio linklayer control protocol (Radio Link Control, RLC) layer; or includes afunction of an RRC/PDCP/media access control (Media Access Control, MAC)layer, and even a partial or entire function of a physical layer PHY.Any other possibilities are not excluded.

The DU has functions of all or some of protocol layers functions of anexisting base station, that is, functional units of some protocol layersof RRC/SDAP/PDCP/RLC/MAC/PHY, for example, includes functions ofprotocol layers such as the PDCP/RLC/MAC/PHY, or includes functions ofsome protocol layers such as the RLC/MAC/PHY, or includes some functionsof the RLC/MAC/PHY, or includes only an entire or partial function ofthe PHY. It should be noted that, the protocol layers mentioned hereinmay change, and all fall within the protection scope of thisapplication.

It should be understood that, the technical solutions in the embodimentsof this application may be applied to various communications systems,such as: a global system for mobile communications (Global System ofMobile Communication, GSM), a code division multiple access (CodeDivision Multiple Access, CDMA) system, a wideband code divisionmultiple access (Wideband Code Division Multiple Access, WCDMA) system,a long term evolution (Long Term Evolution, LTE) system, an LTEfrequency division duplex (Frequency Division Duplex, FDD) system, anLTE time division duplex (Time Division Duplex, TDD) system, a universalmobile telecommunications system (Universal Mobile TelecommunicationsSystem, UMTS), a future 5th-generation (5th-Generation, 5G)communications system, and a CRAN communication system.

It should be further understood that the network device in theembodiments of this application may be a device configured tocommunicate with a terminal device. For example, the network device maybe a combination of a base transceiver station (Base TransceiverStation, BTS) and a base station controller (Base Station Controller,BSC) in a GSM system or CDMA, may be a NodeB (NodeB, NB) and a radionetwork controller (Radio Network Controller, RNC) in a WCDMA system, ormay be an evolved NodeB (Evolutional Node B, eNB or eNodeB) in an LTEsystem. Alternatively, the network device may be a relay station, anaccess point, an in-vehicle device, a wearable device, an access networkdevice in a future 5G network, for example, a next-generation basestation, or an access network device in a future evolved public landmobile network (Public Land Mobile Network, PLMN).

Specifically, there is a scenario in which a radio network control nodeis separated from a base station in a UMTS system in a 3rd-generationmobile communications technology (3rd-Generation, 3G); there is ascenario in which a baseband module is separated from a radio frequencymodule in an LTE system, namely, a radio remote scenario; two differentnetworks need to be interconnected in a data center (Data Center, DC)scenario; in a scenario including macro and micro base stations, thereis an interface for interconnecting the macro and micro base stations;there is an LTE-Wi-Fi aggregation (LTE-Wifi Aggregation, LWA) scenario;there are various non-cell (non-cell) scenarios in a 5G system (aterminal can be freely and randomly handed over between various cells,and there is no definite boundary between the various cells), and onecontrol node is connected to all cells or is connected to varioustransmission nodes in cells; there is a BBU separation scenario in aCRAN scenario; and in a CRAN virtualization scenario, some functions ofa BBU are deployed in a centralized manner and virtualized, the otherfunctions are separately deployed, and there is a possibility that thetwo parts are physically and separately deployed. It should beunderstood that, scenarios of coexistence of different systems/standardsall fall within a scope to which this application is applicable.

The embodiments are described in this application with reference to aterminal device. The terminal device may be user equipment (UserEquipment, UE), an access terminal, a subscriber unit, a subscriberstation, a mobile station, a mobile console, a remote station, a remoteterminal, a mobile device, a user terminal, a terminal, a wirelesscommunication device, a user agent, a user apparatus. The accessterminal may be a cellular phone, a cordless phone, a session initiationprotocol (Session Initiation Protocol, SIP) phone, a wireless local loop(Wireless Local Loop, WLL) station, a personal digital assistant(personal digital assistant, PDA), a handheld device, or a computingdevice having a wireless communication function, another processingdevice connected to a wireless modem, an in-vehicle device, a wearabledevice, a terminal device in a future 5G network, a terminal device in afuture evolved PLMN, or the like.

FIG. 3 is a schematic flowchart of a data transmission method 100according to an embodiment of this application. As shown in FIG. 3 , thefirst network node may correspond to the DU in FIG. 2 , and the secondnetwork node may correspond to the CU in FIG. 2 . The method 100includes the following steps.

S110: The first network node receives a first report from a terminaldevice, where the first report is used to indicate an uplink data volumeof a buffer of the terminal device.

Optionally, the uplink data volume of the buffer of the terminal deviceincludes at least one of a data volume of all radio bearers (RadioBearer, RB) or a specified radio bearer used for uplink transmission ofthe terminal device, a data volume of all logical channels (LogicalChannel, LCH) or a specified logical channel used for uplinktransmission of the terminal device, a data volume of all logicalchannel groups or a specified logical channel group used for uplinktransmission of the terminal device, or a data volume of all quality ofservice flows (Quality of Service, QoS) or a specified quality ofservice flow used for uplink transmission of the terminal device.

Optionally, the first network node includes at least one of a functionof a radio link layer control protocol layer, a function of a mediaaccess control layer, and a function of a physical layer.

Optionally, the second network node includes at least one of a functionof a packet data convergence protocol layer, a function of a servicedata adaptation layer, and a radio resource control function.

It should be understood that, the first report is a buffer status reportBSR, a resource required for transmitting uplink data may be obtained byusing the BSR, and the BSR is used to provide, to a network device,information about a volume of data in an uplink buffer of the terminaldevice that needs to be sent.

For example, the DU receives the BSR sent by the terminal device, theBSR indicates, to the DU, the data volume of the logical channel usedfor the uplink transmission of the terminal device, and based on thedata volume of the logical channel, the DU may notify the CU of the datavolume of the logical channel or notify the CU that the data volume ofthe logical channel is greater than a predefined data volume threshold.

It should be understood that, the first report may alternatively beinformation about the data volume of the buffer of the terminal deviceand MAC control information multiplexed by first information, and thefirst information may be a power headroom report (Power Headroom Report,PHR).

Optionally, the first indication information is further used to instructthe second network node to perform state switching or perform offloadingconfiguration of a radio bearer for the terminal device.

S120: The first network node sends first indication information to thesecond network node, where the first indication information includes theuplink data volume of the buffer of the terminal device, or the firstindication information is used to indicate a relationship between theuplink data volume of the buffer of the terminal device and a predefineddata volume threshold.

It should be understood that, the first indication information is usedto indicate the relationship between the uplink data volume of thebuffer of the terminal device and the predefined data volume threshold,and the relationship between the uplink data volume of the buffer of theterminal device and the predefined data volume threshold may be that theuplink data volume of the buffer of the terminal device is greater than,less than, or equal to the predefined data volume threshold.

It should be further understood that, the first network node request,based on the received information about the uplink data volume of thebuffer of the terminal device, the second network node to switch a stateto an active state, perform carrier aggregation, or perform offloadingconfiguration of a radio bearer for the terminal device.

For example, after receiving the first report sent by the terminaldevice, the DU determines that the uplink data volume of the buffer ofthe terminal device is greater than the predefined data volumethreshold, the DU may send the first indication information to the CU.The first indication information is used to instruct the CU to performstate switching, perform carrier aggregation, or perform offloadingconfiguration of a radio bearer for the terminal device.

Optionally, the method 100 further includes the following step:

S121: The second network node sends second indication information to thefirst network node, where the second indication information is used toindicate the predefined data volume threshold to the first network node,or the second indication information is used to instruct the firstnetwork node to send the information about the uplink data volume of thebuffer of the terminal device to the second network node.

Specifically, after receiving the report sent by the terminal device,the first network node may process the report to learn of the uplinkdata volume of the buffer of the terminal device, and compare the uplinkdata volume of the buffer of the terminal device with the predefineddata volume threshold. The predefined data volume threshold may bepreconfigured by the second network node for the first network node.

Optionally, the second indication information is further used toindicate, to the first network node, a configuration of enabling orforbidding reporting of the information about the data volume.Specifically, the configuration may be a common configuration for theentire first network node, or a configuration for a specified terminaldevice, a specified bearer, a specified logical channel, or a specifieddata flow. For example, if the configuration is a common configuration,information about data volumes of all users is reported.

Optionally, if the first network node is not configured, the firstnetwork node reports information about a data volume of a specifiedservice or a service at a specified QoS level by default.

It should be understood that, the first network node may report, to thesecond network node, a supported reporting capability of the type, sothat the second network node configures the reporting function for thefirst network node.

For example, after receiving the BSR sent by the terminal device, the DUprocesses the BSR to learn of the uplink data volume of the buffer ofthe terminal device from the BSR; the DU compares the uplink data volumeof the buffer of the terminal device with the predefined data volumethreshold preconfigured by the CU; and if the uplink data volume of thebuffer of the terminal device is greater than or equal to the predefineddata volume threshold, the DU sends the first indication information tothe CU; or if the uplink data volume of the buffer of the terminaldevice is less than the predefined data volume threshold, the DU doesnot send the first indication information to the CU.

It should be understood that, if the uplink data volume of the buffer ofthe terminal device is less than the predefined data volume threshold,the DU may alternatively postpone sending the first indicationinformation to the CU.

It should be further understood that, the second network node mayfurther instruct the first network node to configure a mode of reportingthe first indication information to the second network node. The modeincludes an event mode, a periodic mode, and a transparent transmissionmode.

In event mode, a condition for reporting the first indicationinformation may be, but is not limited to, one of the following:

(1) when a total data volume used for the uplink transmission of theterminal device exceeds the predefined data volume threshold;

(2) when the data volume of all the RBs or the specified RB used for theuplink transmission of the terminal device exceeds the predefined datavolume threshold;

(3) when the data volume of all the logical channels or the specifiedlogical channel or all the logical channel groups or the specifiedlogical channel group used for the uplink transmission of the terminaldevice exceeds the predefined data volume threshold;

(4) when the data volume of all the QoS flows or the specified QoS flowused for the uplink transmission of the terminal device exceeds thepredefined data volume threshold; or

(5) when receiving uplink data information during a random accessprocedure performed by the terminal device or after random access iscompleted, the first network node reports the first indicationinformation to the second network node.

A result reported by the first network node may be optionally greaterthan, equal to, or less than the predefined data volume threshold.

For a quantity of times that the first network node performs reporting,optionally, the quantity of times that reporting is performed is greaterthan or equal to 1.

It should be understood that, the quantity of times that reporting isperformed may be configured by the second network node or may be agreedon in a protocol. This is not limited in this application.

In periodic mode, a reporting period may be configured for the firstnetwork node. For example, if the first network node does not receive anew report from the terminal device after previous reporting, the firstnetwork node sends a default value 0 to the second network node.

In event mode and periodic mode, the first network node may collectstatistics on a sum of uplink data volumes of the buffer reported by theterminal device within a period of time, and then compare the sum withthe predefined data volume threshold. For example, if the sum of uplinkdata volumes of the buffer reported by the terminal device exceeds thepredefined data volume threshold, the first network node determines tosend the first indication information to the second network node.

In transparent transmission mode, after receiving a report from theterminal device, the first network node may report the report to thesecond network node in one of the following manners, but this is notlimited thereto:

(1) transparently transmitting the report to the second network node;

(2) extracting content from the report, and reporting originalinformation to the second network node, where, for example, the originalinformation is at least one data volume information of a total datavolume used for the uplink transmission of the terminal device, the datavolume of all the RBs or the specified RB, the data volume of all theLCHs or the specified LCH, the data volume of all the logical channelgroups or the specified logical channel group, and the data volume ofall the QoS flows or the specified QoS flow; or

(3) extracting content from the report, and reporting, based oncomparison with the predefined data volume threshold, a comparisonresult (for example, being greater than, equal to, or less than thepredefined data volume threshold) to the second network node, where forexample, the original information is at least one of a total data volumeused for the uplink transmission of the terminal device, the data volumeof all the RBs or the specified RB, the data volume of all the LCHs orthe specified LCH, the data volume of all the logical channel groups orthe specified logical channel group, and the data volume of all the QoSflows or the specified QoS flow, and the at least one data volume isgreater than or less than the predefined data volume threshold.

S130: The second network node determines, according to the firstindication message, whether to perform state switching or performoffloading configuration of a radio bearer for the terminal device.

Specifically, after the second network node receives the firstindication information sent by the first network node, the secondnetwork node determines whether to perform the state switching orperform the offloading configuration of the radio bearer for theterminal device.

For example, after the CU receives the first indication information sentby the DU, if the first indication information indicates that the uplinkdata volume of the buffer of the terminal device is greater than thepredefined data volume threshold, the CU sends a switching command tothe terminal device. The switching command is used to instruct theterminal device to switch from an inactive state to the active state.

For another example, the CU does not configure the predefined datavolume threshold for the DU, after the CU receives the first indicationinformation sent by the DU, if the first indication informationindicates the uplink data volume of the buffer of the terminal device,the CU may compare the uplink data volume of the buffer of the terminaldevice with the predefined data volume threshold, and if the uplink datavolume of the buffer of the terminal device is greater than thepredefined data volume threshold, the CU sends offloading configurationinformation of the radio bearer to the terminal device.

It should be understood that, in a 5th-generation mobile communicationssystem, to support small data transmission and a power saving mode thatis directly equivalent to an idle (IDLE) state, a third state (theinactive state) is introduced. The determining whether to perform stateswitching for the terminal device may be: determining, by the secondnetwork node, to switch the terminal device from the inactive state tothe active state.

It should be further understood that, the offloading configuration ofthe radio bearer may be a configuration of carrier aggregation (CarrierAggregation, CA) or radio bearer separation. The carrier aggregationmeans that data transmission is provided for the terminal device byusing a plurality of cells, and the plurality of cells may be located inone network node or a plurality of network nodes. The radio bearerseparation means that a plurality of cells provides data transmission onone bearer for the terminal device. When a data volume is relativelylarge, a network instructs the terminal to enter the active state, and adedicated resource is allocated to UE, so that the UE reports channelstate indication information and an uplink channel quality measurementsignal, and the network performs efficient scheduling and sending basedon a channel condition.

According to the data transmission method in this embodiment of thisapplication, when some functions of a network device are separated andserve as different network nodes, the network device can perceive changeinformation of a data volume of a terminal device or a service in time.This prevents the terminal device from redesigning a buffer data volumechange notification for the second network node.

FIG. 4 is another schematic flowchart of a data transmission method 200according to an embodiment of this application. As shown in FIG. 4 , thefirst network node may correspond to the DU in FIG. 2 , and the secondnetwork node may correspond to the CU in FIG. 2 . The method 200includes the following steps.

S210: The second network node sends a first message, where the firstmessage is used to instruct a terminal device to change a key, and thesecond network node includes at least one of a function of a packet dataconvergence protocol layer, a function of a service data adaptationlayer, and a radio resource control function.

Optionally, the first message is an RRC message.

Specifically, the second network node may send the first message to thefirst network node. The first message is used to instruct the terminaldevice to change a key. The first network node includes at least one ofa function of a radio link layer control protocol layer, a function of amedia access control layer, and a function of a physical layer. Thefirst network node may transparently transmit the first message to theterminal device. After receiving the first message, the terminal devicededuces a new key, selects a random access slot, and sends a randomaccess preamble sequence (preamble) to the first network node.

For example, the CU sends an RRC message to the DU. The RRC message isused to instruct the terminal device to change a key. After receivingthe RRC message, the DU transparently transmits the RRC message to theterminal device, and the terminal device sends a preamble to the DU.

Optionally, if an uplink grant configuration parameter used by theterminal device to send data on an uplink is allocated in the firstmessage, the terminal device may send data on the uplink grant by usinga proper extended prefix format, without selecting a random access slotfor sending the random access preamble sequence.

Optionally, FIG. 5 is still another schematic flowchart of the datatransmission method 200 according to an embodiment of this application.As shown in FIG. 5 , the method 200 further includes the followingsteps:

S211: The second network node sends a first message to the first networknode, where the first message is used to instruct the terminal device tochange a key.

S212: The first network node sends a second message to the terminaldevice, where the second message includes a dedicated random accesspreamble sequence of the terminal device.

Optionally, the first message includes the dedicated random accesspreamble sequence of the terminal device, or the second network nodesends the first message and the dedicated random access preamblesequence of the terminal device to the first network node.

Specifically, the preamble is the dedicated random access preamblesequence of the terminal device, and the dedicated random accesspreamble sequence of the terminal device is managed by the secondnetwork node. The second network node sends the first message to thefirst network node, where the first message includes the dedicatedrandom access preamble sequence of the terminal device; or the secondnetwork node sends the first message and the dedicated random accesspreamble sequence of the terminal device to the first network node. Thefirst network node may transparently transmit the first message and thededicated random access preamble sequence of the terminal device to theterminal device.

For example, the CU sends a first RRC message to the DU, where the firstRRC message includes the dedicated random access preamble sequence ofthe terminal device, or the CU sends a first RRC message and thededicated random access preamble sequence of the terminal device to theDU, where the first RRC message is used to instruct the terminal deviceto change a key. The DU may transparently transmit the first message andthe dedicated random access preamble sequence of the terminal device tothe terminal device.

It should be understood that, the first message and the second messagemay have same content.

It should be further understood that, the dedicated random accesspreamble sequence of the terminal device may be reserved by the secondnetwork node, or may be allocated by the first network node to thesecond network node.

Optionally, as shown in FIG. 5 , the method 200 further includes thefollowing steps:

S213: The first network node receives a preamble sequence requestmessage sent by the second network node.

S214: The first network node sends the dedicated random access preamblesequence of the terminal device to the second network node based on thepreamble sequence request message.

Specifically, the preamble is the dedicated random access preamblesequence of the terminal device, and the dedicated random accesspreamble sequence of the terminal device is managed by the first networknode. The second network node sends the preamble sequence requestmessage to the first network node, where the preamble sequence requestmessage is used to request the dedicated random access preamble sequenceof the terminal device from the first network node. The first networknode sends the dedicated random access preamble sequence of the terminaldevice to the second network node based on the preamble sequence requestmessage, and the second network node delivers the dedicated randomaccess preamble sequence of the terminal device to the terminal device.

It should be understood that, the dedicated random access preamblesequence of the terminal device is managed by the first network node.The first message sent by the second network node to the first networknode does not include the dedicated random access preamble sequence, andthe first network node may add the dedicated random access preamblesequence to the sent second message, or the first network node may sendthe second message and the dedicated random access preamble sequence tothe terminal device.

For example, the CU sends the first RRC message to the DU, where thefirst RRC message is used to instruct the terminal device to change akey. After receiving the first RRC message, the DU seconds a second RRCmessage to the terminal device, where the second RRC message includesthe dedicated random access preamble sequence of the terminal device, orthe DU sends a second RRC message and the dedicated random accesspreamble sequence of the terminal device to the terminal device, orbefore sending the first RRC message to the DU, the CU requests the DUto allocate the dedicated random access preamble sequence, the DU sendsthe dedicated random access preamble sequence to the CU, and the CU addsthe dedicated random access preamble sequence to the first RRC messageand sends the first RRC message to the terminal by using the DU.

FIG. 6 is still another schematic flowchart of the data transmissionmethod 200 according to an embodiment of this application. As shown inFIG. 6 , the method 200 further includes the following steps:

S215: The second network node sends a first message to the first networknode, where the first message is used to instruct the terminal device tochange a key.

S216: The first network node sends a second message to the terminaldevice, where the second message includes an uplink grant configurationparameter used by the terminal device to send data.

Optionally, the first message includes the uplink grant configurationparameter of the terminal device, or the second network node sends thefirst message and the uplink grant configuration parameter to the firstnetwork node.

Specifically, the uplink grant configuration parameter is managed by thesecond network node. The second network node sends the first message tothe first network node, where the first message includes the uplinkgrant configuration parameter of the terminal device, or the secondnetwork node sends the first message and the uplink grant configurationparameter to the first network node, where the first network node maytransparently transmit the first message and the uplink grantconfiguration parameter to the terminal device.

It should be understood that, the first message and the second messagemay have same content.

For example, the CU sends the first RRC message to the DU, where thefirst RRC message includes the uplink grant configuration parameter ofthe terminal device, or the CU sends the first RRC message and theuplink grant configuration parameter of the terminal device to the DU,where the first RRC message is used to instruct the terminal device tochange a key. The DU may transparently transmit the first message andthe uplink grant configuration parameter of the terminal device to theterminal device.

It should be understood that, if an uplink grant configuration parameterused by the terminal device to send data on an uplink is allocated inthe second message, the terminal device may send data on the uplinkgrant by using a proper extended prefix format, without selecting arandom access slot for sending the random access preamble sequence.

It should be further understood that, the uplink grant configurationparameter of the terminal device that is used to send data may bereserved by the second network node, or may be actively allocated by thefirst network node to the second network node, or may be activelyallocated by the first network node to the second network node when thesecond network node requests the uplink grant configuration parameter.

Optionally, as shown in FIG. 6 , the method 200 further includes thefollowing steps:

S217: The first network node receives an uplink grant configurationparameter request message sent by the second network node.

S218: The first network node sends the uplink grant configurationparameter to the second network node based on the uplink grantconfiguration parameter request message.

Specifically, the uplink grant configuration parameter is managed by thefirst network node. The second network node sends the uplink grantconfiguration parameter request message to the first network node, wherethe uplink grant configuration parameter request message is used torequest the uplink grant configuration parameter of the terminal devicefrom the first network node. The first network node sends the uplinkgrant configuration parameter of the terminal device to the secondnetwork node based on the uplink grant configuration parameter requestmessage, and the second network node delivers the uplink grantconfiguration parameter of the terminal device to the terminal device.

It should be understood that, the uplink grant configuration parameterof the terminal device is managed by the first network node. The firstmessage sent by the second network node to the first network node doesnot include the uplink grant configuration parameter, and the firstnetwork node may add the uplink grant configuration parameter to thesent second message, or the first network node may send the secondmessage and the uplink grant configuration parameter to the terminaldevice. As shown in FIG. 6 , the method 200 further includes thefollowing step:

S241: The terminal device sends uplink data to the first network node onan uplink grant.

Optionally, as shown in FIG. 4 , the method 200 further includes thefollowing steps.

S220: The terminal device sends a random access preamble sequence to thefirst network node.

Specifically, as shown in FIG. 4 , if the random access preamblesequence is not the dedicated random access preamble sequence of theterminal device, after receiving the random access preamble sequence,the first network node sends a random access response message to theterminal device, and allocates an uplink scheduling grant (UL grant) tothe terminal device.

S230: The first network node sends a random access response to theterminal device.

S240: The first network node receives the uplink data sent by theterminal.

Specifically, after receiving the random access response message sent bythe first network node, the terminal device sends the uplink data to thefirst network node, where the uplink data includes a key change responsemessage.

Optionally, if the random access preamble sequence in S220 is not therandom access preamble sequence of the terminal device, the uplink dataincludes identifier information of the terminal device.

Optionally, the identifier information of the terminal device is a cellradio network temporary identifier (C-RNTI) or context identifierinformation.

Optionally, as shown in FIG. 5 , the random access preamble sequence isthe dedicated random access preamble sequence of the terminal device,and the method 200 further includes the following step.

S221: The terminal device sends the dedicated random access preamblesequence of the terminal device to the first network node.

It should be understood that, as shown in FIG. 5 , after the firstnetwork node receives the dedicated preamble of the terminal device,S240 of sending, by the terminal device, the uplink data to the firstnetwork node is optional, and in S250, the first network node sendsthird indication information to the second network node, where the thirdindication information indicates that the terminal device has performeda random access procedure. It is not excluded that the third indicationinformation includes the dedicated preamble or the identifierinformation of the terminal device, and it is not excluded that thethird indication information is transmitted by using a commontransmission channel.

It should be further understood that, as shown in FIG. 6 , if theterminal device receives the uplink grant configuration parameter inS216, after a new key is used for protection, the terminal device sendsdata on the allocated uplink grant, and S220 and S230 are optional.

S250: The first network node sends third indication information to thesecond network node, where the third indication information is used toindicate, to the second network node, that the uplink data is uplinkdata that is sent in a random access procedure or after a random accessprocedure or on the uplink grant, or the third indication information isused to indicate, to the second network node, that the terminal devicehas performed a random access procedure, and the second network nodeincludes at least one of a function of a packet data convergenceprotocol layer, a function of a service data adaptation layer, and aradio resource control function.

Optionally, the uplink data sent on the uplink grant is uplink data senton an uplink grant allocated in the first message.

It should be understood that, the third indication information may becontrol signaling information, or may be indication information carriedin user plane data.

It should be further understood that, if the terminal device sends thededicated random access preamble sequence of the terminal device to thefirst network node, the third indication information is used toindicate, to the second network node, that the terminal device hasperformed the random access procedure.

For example, after receiving the dedicated preamble or receiving thedata on the uplink grant or receiving MSG3 data, the first network nodenotifies the second network node that the terminal device has alreadyswitched to a new key, or indicates that the terminal device has alreadyused a random access procedure, to implicitly indicate that the terminaldevice has already switched to a new key.

Specifically, after receiving the uplink data sent by the terminaldevice, the first network node indicates, to the second network node inan explicit or implicit manner, that the uplink data is uplink data thatis sent in the random access procedure or after the random accessprocedure by using a semi-statically allocated uplink grant, and theuplink data is data protected by using the new key. In other words, thefirst network node indicates, in an explicit or implicit manner, thatthe terminal device has performed the random access, is performing therandom access, or performs no random access, to send and transform dataprotected by using different keys, and the second network node may learnthat the terminal device has already completely deduced the new key, andhas performed sending by using the new key.

Optionally, the first network node sends the third indicationinformation to the second network node on a dedicated bearer, where thededicated bearer is a dedicated bearer between the first network nodeand the second network node that corresponds to the terminal device.

For example, the DU sends the third indication information on adedicated bearer between the CU and the DU, explicitly indicates thatthe terminal device uses the random access procedure, and then sends theuplink data.

Optionally, the first network node sends the third indicationinformation to the second network node on a common channel, where thecommon channel is a channel between the first network node and thesecond network node that is used by the terminal device to send theuplink data in the random access procedure.

For example, the DU sends the identifier information and/or the uplinkdata of the terminal device to the CU on a channel between the CU andthe DU that is used to transmit the uplink data sent by the terminaldevice in the random access procedure, and the CU determines, by usingthe channel, that the terminal device has performed the random accessprocedure.

It should be understood that, after receiving the dedicated randomaccess preamble sequence, the first network node may directly send thethird indication information to the second network node in an explicitor implicit manner, and send a random access response message to theterminal device. In the explicit manner, the third indicationinformation indicates that the terminal device sends data through randomaccess or by using a preconfigured uplink grant. In the implicit manner,the third indication information is sent on a common transmission tunnelused to send uplink information received in the random access procedure,and indicates that the terminal device has performed the random accessprocedure.

It should be further understood that, if the random access preamblesequence is not the dedicated random access preamble sequence of theterminal device, the third indication information includes theidentifier information of the terminal device.

It should be further understood that, the identifier information is thecell radio network temporary identifier or the context identifierinformation of the terminal device.

According to the data transmission method in this embodiment of thisapplication, when some functions of a network device are separated andserve as different network nodes, the second network node can perceive,in time, that a terminal device has performed a random access procedure,and the second network node can implicitly perceive that a key of theterminal device has already been changed completely.

FIG. 7 is still another schematic flowchart of a data transmissionmethod 300 according to an embodiment of this application. As shown inFIG. 7 , the first network node may correspond to the DU in FIG. 2 , andthe second network node may correspond to the CU in FIG. 2 . The method300 includes the following steps:

S310: A terminal device determines that there is first data in a bufferof the terminal device or a data volume of first data exceeds apredefined data volume threshold or a discard timer of first dataexpires within a predefined time length.

S320: The terminal device triggers a second report, where the secondreport is used to indicate that the first data in the buffer of theterminal device needs to be sent.

Specifically, if there is important data in the buffer of the terminaldevice or a data volume of important data exceeds the predefined datavolume threshold or a discard timer of important data expires within thepredefined time length, the terminal device triggers the second report,where the second report is used to indicate that the important data inthe buffer of the terminal device needs to be sent.

For example, when a length of a PDCP discard timer of the first data isconfigured as 150 ms, and the first data has waited for 100 ms in a PDCPbuffer and expires after 50 ms (the predefined time length), UEconsiders that a report of the first data can be triggered.

For another example, when the data volume of the first data exceeds 200bytes (the predefined data volume threshold), UE considers that a reportof the first data can be triggered.

It should be understood that, a retransmission timer may be startedafter the second report is sent. After the timer expires, if theterminal device determines that there is the first data in the buffer ofthe terminal device, the second report may be triggered again.

It should be further understood that, if the second report supportsperiodic triggering, a periodic timer may be started after thetriggering, and after the timer expires, if the terminal devicedetermines that there is the first data in the buffer of the terminaldevice, the second report may be triggered again.

Optionally, the predefined time length and the predefined data volumethreshold may both be configured in a network or agreed on in aprotocol.

Optionally, before the triggering, by the terminal device, a secondreport, the method 300 further includes the following step:

S311: The terminal device sends a third message to a third network node,where the third message is used to indicate that the terminal devicesupports a mode of triggering the second report.

It should be understood that, the third message may be used to indicatethat the terminal device supports a mode of triggering the second reportby using a specified logical channel or bearer.

A mode of triggering the second report by the terminal device may be,but is not limited to, one of the following:

(1) if the indicated logical channel or bearer changes from having noimportant data to having important data;

(2) if the indicated logical channel or bearer has important data andthe discard timer (discard timer) is to expire within the predefinedtime length, for example, 50 ms;

(3) if a data volume of important data on the indicated logical channelor bearer exceeds the predefined data volume threshold; or

(4) if important data is completely sent on the indicated logicalchannel or bearer.

For example, the terminal device determines that there is a data packetof an I frame of a real-time video in the buffer of the terminal deviceor the data packet of the I frame exceeds the predefined data volumethreshold or a discard timer of the data packet of the I frame expireswithin the predefined time length, the terminal device sends a BSR tothe third network node, where the BSR is used to indicate that the datapacket of the I frame of the real-time video in the buffer of theterminal device needs to be sent.

Optionally, before the triggering, by the terminal device, a secondreport, the method 300 further includes the following step:

S312: The terminal device receives a fourth indication message sent bythe third network node, where the fourth indication message is used toinstruct the terminal device to trigger the second report on a specifiedlogical channel or bearer.

For example, the third network node instructs the terminal device totrigger the mode on the specified bearer or logical channel. Forexample, for a bearer having a QCI=2, the terminal device can triggeronly reporting indication information of the important data on thebearer.

For another example, it is agreed on in a protocol that reportingindication information of the important data can be triggered on only abearer having a QCI=2.

It should be understood that, only the important data (the first data)being the data packet of the I frame of the real-time video is describedabove, and the important data is not limited thereto. For example, theimportant data may alternatively be a data packet of an associatedbidirectional P frame. The important data is not limited in thisapplication.

Optionally, the terminal device may trigger the second report in one ofthe following manners, but this is not limited thereto:

(1) a bit of a MAC BSR subheader indicates that there is importantdata/there is no important data;

(2) in an implementation in replacement of MAC BSR reporting, a newmedia access control control element (MAC CE) is introduced, the MAC CEis a media access control service data unit (MAC SDU) of 0 bytes, and aspecial LCH ID indicates the important data in a MAC subheader; or

(3) in another implementation in replacement of MAC BSR reporting, a newMAC CE is introduced, a special LCH ID indicates the important data in aMAC subheader, the MAC CE is a MAC SDU of 1 byte, and the MAC SDUindicates a volume of the important data or a data volume threshold.

Optionally, the third network node includes at least one of a functionof a radio resource control protocol layer, a function of a packet dataconvergence protocol layer, a function of a radio link layer controlprotocol layer, a function of a media access control layer, and afunction of a physical layer.

It should be understood that, in a possible implementation, a networkinstructs the terminal device to receive the fourth indication messagesent by the third network node, where the fourth indication message isused to instruct the terminal device to trigger the second report.

It should be understood that, in a possible implementation, the terminaldevice reports capability information for supporting triggering of thesecond report, and a network determines, based on a capability of theterminal device, to instruct to enable the triggering function.

It should be understood that, the third network node may be a basestation, or may be the DU in an architecture including the CU and theDU. The third network node is not limited in this application.

According to the data transmission method in this embodiment of thisapplication, when there is important data in the buffer of the terminaldevice, a network device can be notified in time.

The data transmission methods according to the embodiments of thisapplication are described in detail above with reference to FIG. 1 toFIG. 7 . A network device and a terminal device according to embodimentsof this application are described in detail below with reference to FIG.8 to FIG. 27 .

FIG. 8 is a schematic block diagram of a network device 400 according toan embodiment of this application. As shown in FIG. 8 , the networkdevice 400 includes:

a transceiver module 410, configured to receive a first report from aterminal device, where the first report is used to indicate an uplinkdata volume of a buffer of the terminal device; and

a processing module 420, configured to generate first indicationinformation, where the first indication information includes the uplinkdata volume of the buffer of the terminal device, or the firstindication information is used to indicate a relationship between theuplink data volume of the buffer of the terminal device and a predefineddata volume threshold, where

the transceiver module 410 is further configured to send the firstindication information to a second network node.

Optionally, the first report is a buffer status report BSR.

In some possible implementations, the first report is the information ofthe data volume of the buffer of the terminal device and MAC controlinformation multiplexed by first information, and the first informationmay be a power headroom report.

In some possible implementations, the first indication information isfurther used to instruct the second network node to perform stateswitching or perform offloading configuration of a radio bearer for theterminal device.

Optionally, the uplink data volume of the buffer of the terminal deviceincludes at least one of a data volume of all radio bearers or aspecified radio bearer used for uplink transmission of the terminaldevice, a data volume of all logical channels or a specified logicalchannel used for uplink transmission of the terminal device, a datavolume of all logical channel groups or a specified logical channelgroup used for uplink transmission of the terminal device, or a datavolume of all quality of service flows or a specified quality of serviceflow used for uplink transmission of the terminal device.

Optionally, the transceiver module 410 is further configured to receivesecond indication information sent by the second network node, where thesecond indication information is used to indicate the predefined datavolume threshold or the uplink data volume to the first network node;and

the transceiver module 410 is specifically configured to send the firstindication information to the second network node based on thepredefined data volume threshold or the uplink data volume.

Optionally, if the uplink data volume of the buffer of the terminaldevice is greater than or equal to the predefined data volume threshold,the transceiver module 410 sends the first indication information to thesecond network node.

Optionally, the network device includes at least one of a function of aradio link layer control protocol layer, a function of a media accesscontrol layer, and a function of a physical layer; and/or the secondnetwork node includes at least one of a function of a packet dataconvergence protocol layer, a function of a service data adaptationlayer, and a radio resource control function.

Optionally, the second indication information is used to instruct thefirst network node to enable reporting of the first indicationinformation; and the transceiver module 410 is specifically configuredto send the first indication information to the second network nodeaccording to the second indication information.

When some functions of the network device in this embodiment of thisapplication are separated and serve as different network nodes, thenetwork device can perceive change information of a data volume of aterminal device or a service in time. This prevents the terminal devicefrom redesigning a buffer data volume change notification for the secondnetwork node.

FIG. 9 is a schematic block diagram of a network device 500 according toan embodiment of this application. As shown in FIG. 9 , the networkdevice 500 includes:

a transceiver module 510, configured to receive a first indicationmessage sent by a first network node, where the first indication messageis used to indicate an uplink data volume of a buffer of the terminaldevice to the second network node, or the first indication informationis used to indicate a relationship between an uplink data volume of abuffer of the terminal device and a predefined data volume threshold;and

a processing module 520, configured to determine, according to the firstindication message, whether to perform state switching or performoffloading configuration of a radio bearer for the terminal device.

Optionally, the uplink data volume of the buffer of the terminal deviceincludes at least one of a data volume of all radio bearers or aspecified radio bearer used for uplink transmission of the terminaldevice, a data volume of all logical channels or a specified logicalchannel used for uplink transmission of the terminal device, a datavolume of all logical channel groups or a specified logical channelgroup used for uplink transmission of the terminal device, or a datavolume of all quality of service flows or a specified quality of serviceflow used for uplink transmission of the terminal device.

Optionally, the transceiver module 510 is further configured to sendsecond indication information to the first network node, where thesecond indication information is used to indicate the predefined datavolume threshold or the uplink data volume to the first network node.

Optionally, the second indication information is further used toinstruct the first network node to send the first indication informationto the second network node if the uplink data volume of the buffer ofthe terminal device is greater than or equal to the predefined datavolume threshold.

Optionally, the state switching includes switching from an inactivestate to an active state.

Optionally, the first network node includes at least one of a functionof a radio link layer control protocol layer, a function of a mediaaccess control layer, and a function of a physical layer; and/or thenetwork device includes at least one of a function of a packet dataconvergence protocol layer, a function of a service data adaptationlayer, and a radio resource control function.

Optionally, the second indication information is used to instruct thefirst network node to enable reporting of the information about the datavolume.

Optionally, the second indication information is used to instruct thefirst network node to enable reporting of the information about the datavolume for a specified terminal device, a specified bearer, or aspecified logical channel.

FIG. 10 is a schematic block diagram of a terminal device 600 accordingto an embodiment of this application. As shown in FIG. 10 , the terminaldevice 600 includes:

a processing module 610, configured to generate a first report, wherethe first report is used to indicate an uplink data volume of a bufferof the terminal device; and

a transceiver module 620, configured to send the first report to a firstnetwork node, where the transceiver module is further configured toreceive indication information sent by a second network node, where theindication information is used to determine whether to perform stateswitching or perform offloading configuration of a radio bearer for theterminal device.

Optionally, the first report is a buffer status report BSR.

Optionally, the first report is the information of the data volume ofthe buffer of the terminal device and MAC control informationmultiplexed by first information, and the first information may be apower headroom report.

Optionally, the first indication information is further used to instructthe second network node to perform state switching or perform offloadingconfiguration of a radio bearer for the terminal device.

Optionally, the uplink data volume of the buffer of the terminal deviceincludes at least one of a data volume of all radio bearers or aspecified radio bearer used for uplink transmission of the terminaldevice, a data volume of all logical channels or a specified logicalchannel used for uplink transmission of the terminal device, a datavolume of all logical channel groups or a specified logical channelgroup used for uplink transmission of the terminal device, or a datavolume of all quality of service flows or a specified quality of serviceflow used for uplink transmission of the terminal device.

Optionally, the first network node includes at least one of a functionof a radio link layer control protocol layer, a function of a mediaaccess control layer, and a function of a physical layer; and/or thesecond network node includes at least one of a function of a packet dataconvergence protocol layer, a function of a service data adaptationlayer, and a radio resource control function.

FIG. 11 is a schematic block diagram of a network device 700 accordingto an embodiment of this application. As shown in FIG. 11 , the networkdevice 700 includes:

a transceiver module 710, configured to receive uplink data sent by aterminal, where the network device includes at least one of a functionof a radio link layer control protocol layer, a function of a mediaaccess control layer, and a function of a physical layer; and

a processing module 720, configured to generate third indicationinformation, where the third indication information is used to indicate,to the second network node, that the uplink data is uplink data that issent in a random access procedure or after random access or uplink datathat is sent on an uplink grant, where

the transceiver module 710 is further configured to send the thirdindication information to the second network node, where the secondnetwork node includes at least one of a function of a packet dataconvergence protocol layer, a function of a service data adaptationlayer, and a radio resource control function.

Optionally, the transceiver module 710 is further configured to: receivea random access preamble sequence sent by the terminal device; and senda random access response to the terminal device.

Optionally, the transceiver module 710 is specifically configured toreceive, on the uplink grant, the uplink data sent by the terminaldevice.

Optionally, the transceiver module 710 is specifically configured tosend the third indication information to the second network node on adedicated bearer, where the dedicated bearer is a dedicated bearerbetween the first network node and the second network node thatcorresponds to the terminal device.

Optionally, the transceiver module 710 is specifically configured tosend the third indication information to the second network node on acommon channel, where the common channel is a channel between the firstnetwork node and the second network node that is used by the terminaldevice to send the uplink data in the random access procedure.

Optionally, the third indication information includes identifierinformation of the terminal device.

Optionally, the transceiver module 710 is further configured to send anuplink grant configuration parameter of the terminal device to theterminal device.

Optionally, the transceiver module 710 is further configured to receivean uplink grant configuration parameter request message sent by thesecond network node; and

the processing module 720 is further configured to control, based on theuplink grant configuration parameter request message, the transceivermodule 710 to send the uplink grant configuration parameter to thesecond network node.

Optionally, the transceiver module 710 is further configured to receivethe uplink grant configuration parameter sent by the second networknode.

Optionally, the identifier information is a cell radio network temporaryidentifier or context identifier information of the terminal device.

According to the network device in this embodiment of this application,when some functions of the network device are separated and serve asdifferent network nodes, the second network node can perceive, in time,that a terminal device has performed a random access procedure, and thesecond network node can implicitly perceive that a key of the terminaldevice has already been changed completely.

FIG. 12 is a schematic block diagram of a network device 800 accordingto an embodiment of this application. As shown in FIG. 12 , the networkdevice 800 includes:

a transceiver module 810, configured to receive a dedicated randomaccess preamble sequence sent by the terminal, where the network deviceincludes at least one of a function of a radio link layer controlprotocol layer, a function of a media access control layer, and afunction of a physical layer; and

a processing module 820, configured to generate third indicationinformation, where the third indication information is used to indicate,to the second network node, that the terminal device has performed arandom access procedure, where

the transceiver module 810 is further configured to send the thirdindication information to the second network node, where the secondnetwork node includes at least one of a function of a packet dataconvergence protocol layer, a function of a service data adaptationlayer, and a radio resource control function.

Optionally, the transceiver module 810 is specifically configured tosend the third indication information to the second network node on adedicated bearer, where the dedicated bearer is a dedicated bearerbetween the first network node and the second network node thatcorresponds to the terminal device.

Optionally, the transceiver module 810 is specifically configured tosend the third indication information to the second network node on acommon channel, where the common channel is a channel between the firstnetwork node and the second network node that is used by the terminaldevice to send the uplink data in the random access procedure.

Optionally, the third indication information includes the dedicatedrandom access preamble sequence or identifier information of theterminal device.

Optionally, the transceiver module 810 is further configured to send thededicated random access preamble sequence to the terminal device.

Optionally, the transceiver module 810 is further configured to receivea preamble sequence request message sent by the second network node; and

the processing module 820 is further configured to control, based on thepreamble sequence request message, the transceiver module 810 to sendthe dedicated random access preamble sequence to the second networknode.

Optionally, the transceiver module 810 is further configured to receivethe dedicated random access preamble sequence sent by the second networknode.

Optionally, the identifier information is a cell radio network temporaryidentifier or context identifier information of the terminal device.

According to the network device in this embodiment of this application,when some functions of the network device are separated and serve asdifferent network nodes, the second network node can perceive, in time,that a terminal device has performed a random access procedure, and thesecond network node can implicitly perceive that a key of the terminaldevice has already been changed completely.

FIG. 13 is a schematic block diagram of a network device 900 accordingto an embodiment of this application. As shown in FIG. 13 , the networkdevice 900 includes:

a processing module 910, configured to generate a first message, wherethe first message is used to instruct a terminal device to change a key;and

a transceiver module 920, configured to send the first message, wherethe network device includes at least one of a function of a packet dataconvergence protocol layer, a function of a service data adaptationlayer, and a radio resource control function, where

the transceiver module 920 is further configured to receive thirdindication information sent by the first network node, where the thirdindication information is used to indicate, to the second network node,that uplink data received by the first network node is uplink data thatis sent in a random access procedure or after a random access procedureor uplink data sent on an uplink grant, or the third indicationinformation is used to indicate, to the second network node, that theterminal device has performed a random access procedure, and the firstnetwork node includes at least one of a function of a radio link layercontrol protocol layer, a function of a media access control layer, anda function of a physical layer.

Optionally, the first message includes a dedicated random accesspreamble sequence of the terminal device or an uplink grantconfiguration parameter used to send data.

Optionally, the transceiver module 920 is specifically configured toreceive, on a dedicated bearer, the third indication information sent bythe second network node, where the dedicated bearer is a dedicatedbearer between the first network node and the second network node thatcorresponds to the terminal device.

Optionally, the transceiver module 920 is specifically configured toreceive, on a common channel, the third indication information sent bythe second network node, where the common channel is a channel betweenthe first network node and the second network node that is used by theterminal device to send the uplink data in the random access procedure.

Optionally, the third indication information includes the dedicatedrandom access preamble sequence of the terminal device or identifierinformation of the terminal device.

Optionally, the transceiver module 920 is further configured to send apreamble sequence request message or an uplink grant configurationparameter request message to the first network node; and the secondnetwork node receives the dedicated random access preamble sequence sentby the first network node or an uplink grant configuration parameterused to send data.

Optionally, the transceiver module 920 is further configured to send, tothe first network node, the dedicated random access preamble sequence orthe uplink grant configuration parameter used to send data.

Optionally, the identifier information is a cell radio network temporaryidentifier or context identifier information of the terminal device.

FIG. 14 is a schematic block diagram of a terminal device 1000 accordingto an embodiment of this application. As shown in FIG. 14 , the terminaldevice 1000 includes:

a transceiver module 1010, configured to receive a first message from asecond network node, where the first message is used to instruct theterminal device to change a key, and the second network node includes atleast one of a function of a packet data convergence protocol layer, afunction of a service data adaptation layer, and a radio resourcecontrol function; and

a processing module 1020, configured to control the transceiver moduleto be further configured to send uplink data to a first network node,where the first network node includes at least one of a function of aradio link layer control protocol layer, a function of a media accesscontrol layer, and a function of a physical layer.

Optionally, the transceiver module 1010 is further configured to: send arandom access preamble sequence to the first network node; and receive arandom access response sent by the first network node.

Optionally, the transceiver module 1010 is further configured to receivean uplink grant configuration parameter; and the transceiver module 1010is specifically configured to send the uplink data to the first networknode on an uplink grant.

Optionally, the first message includes the uplink grant configurationparameter of the terminal device.

Optionally, the uplink data includes identifier information of theterminal device.

Optionally, the identifier information is a cell radio network temporaryidentifier or context identifier information of the terminal device.

Optionally, the transceiver module 1010 is further configured to receivethe dedicated random access preamble sequence sent by the first networknode or an uplink grant configuration parameter used to send data.

FIG. 15 is a schematic block diagram of a terminal device 1100 accordingto an embodiment of this application. As shown in FIG. 15 , the terminaldevice 1100 includes:

a transceiver module 1110, configured to receive a first message from asecond network node, where the first message is used to instruct theterminal device to change a key, and the second network node includes atleast one of a function of a packet data convergence protocol layer, afunction of a service data adaptation layer, and a radio resourcecontrol function; and

a processing module 1120, configured to control the transceiver moduleto further configured to send a dedicated random access preamblesequence of the terminal device to a first network node, where the firstnetwork node includes at least one of a function of a radio link layercontrol protocol layer, a function of a media access control layer, anda function of a physical layer.

Optionally, the first message includes the dedicated random accesspreamble sequence of the terminal device.

Optionally, the transceiver module 1110 is further configured to receivethe dedicated random access preamble sequence of the terminal devicesent by the first network node.

FIG. 16 is a schematic block diagram of a terminal device 1200 accordingto an embodiment of this application. As shown in FIG. 16 , the terminaldevice 1200 includes:

a processing module 1210, configured to determine that there is firstdata in a buffer of the terminal device or a data volume of first dataexceeds a predefined data volume threshold or a discard timer of firstdata expires within a predefined time length; and

a transceiver module 1220, configured to trigger a second report, wherethe second report is used to indicate that the first data in the bufferof the terminal device needs to be sent.

Optionally, the transceiver module 1220 is further configured to receivefourth indication information sent by a third network node, where thefourth indication information is used to instruct the terminal device tosend the data report on a specified logical channel or bearer.

Optionally, the third network node includes at least one of a functionof a radio resource control protocol layer, a function of a packet dataconvergence protocol layer, a function of a radio link layer controlprotocol layer, a function of a media access control layer, and afunction of a physical layer.

Optionally, the first data is data considered to be relatively importanton a bearer. For example, an I frame or a bidirectional P frame in videoframes is data more important than a unidirectional P frame. It is notexcluded that definition of importance may be agreed on by an operatoror an application provider and a user. This is not limited herein.

According to the terminal device in this embodiment of this application,when there is the important data in the buffer of the terminal device, anetwork device can be notified in time.

FIG. 17 is a schematic block diagram of a network device 1300 accordingto an embodiment of this application. As shown in FIG. 17 , the networkdevice 1300 includes:

a processing module 1310, configured to generate fourth indicationinformation, where the fourth indication information is used to instructthe terminal device to send a second report on a specified logicalchannel or bearer, and the second report is used to indicate that thefirst data in a buffer of the terminal device needs to be sent; and

a transceiver module 1320, configured to send fourth indicationinformation to the terminal device, where

the transceiver module 1320 is further configured to receive the secondreport on the specified logical channel or bearer.

Optionally, the third network node includes at least one of a functionof a radio resource control protocol layer, a function of a packet dataconvergence protocol layer, a function of a radio link layer controlprotocol layer, a function of a media access control layer, and afunction of a physical layer.

Optionally, the first data is data considered to be relatively importanton a bearer. For example, an I frame or a bidirectional P frame in videoframes is data more important than a unidirectional P frame. It is notexcluded that definition of importance may be agreed on by an operatoror an application provider and a user. This is not limited herein.

FIG. 18 is a schematic structural diagram of a network device 1400according to an embodiment of this application. As shown in FIG. 18 ,the network device 1400 includes a processor 1401, a memory 1402, areceiver 1403, and a transmitter 1404. These components communicate withand are connected to each other. The memory 1402 is configured to storean instruction. The processor 1401 is configured to: execute theinstruction stored in the memory 1402, control the receiver 1403 toreceive information, and control the transmitter 1404 to sendinformation.

The processor 1401 is configured to execute the instruction stored inthe memory 1402, the processor 1401 may be configured to perform acorresponding operation and/or function of the processing module 420 inthe network device 400, and the receiver 1403 and the transmitter 1404may be configured to perform a corresponding operation and/or functionof the transceiver module 410 in the network device 400. For brevity,details are not described herein again.

FIG. 19 is a schematic structural diagram of a network device 1500according to an embodiment of this application. As shown in FIG. 19 ,the network device 1500 includes a processor 1501, a memory 1502, areceiver 1503, and a transmitter 1504. These components communicate withand are connected to each other. The memory 1502 is configured to storean instruction. The processor 1501 is configured to: execute theinstruction stored in the memory 1502, control the receiver 1503 toreceive information, and control the transmitter 1504 to sendinformation.

The processor 1501 is configured to execute the instruction stored inthe memory 1502, the processor 1501 may be configured to perform acorresponding operation and/or function of the processing module 520 inthe network device 500, and the receiver 1503 and the transmitter 1504may be configured to perform a corresponding operation and/or functionof the transceiver module 510 in the network device 500. For brevity,details are not described herein again.

FIG. 20 is a schematic structural diagram of a terminal device 1600according to an embodiment of this application. As shown in FIG. 20 ,the terminal device 1600 includes a processor 1601, a memory 1602, areceiver 1603, and a transmitter 1604. These components communicate withand are connected to each other. The memory 1602 is configured to storean instruction. The processor 1601 is configured to: execute theinstruction stored in the memory 1602, control the receiver 1603 toreceive information, and control the transmitter 1604 to sendinformation.

The processor 1601 is configured to execute the instruction stored inthe memory 1602, the processor 1601 may be configured to perform acorresponding operation and/or function of the processing module 610 inthe terminal device 600, and the receiver 1603 and the transmitter 1604may be configured to perform a corresponding operation and/or functionof the transceiver module 620 in the terminal device 600. For brevity,details are not described herein again.

FIG. 21 is a schematic structural diagram of a network device 1700according to an embodiment of this application. As shown in FIG. 21 ,the network device 1700 includes a processor 1701, a memory 1702, areceiver 1703, and a transmitter 1704. These components communicate withand are connected to each other. The memory 1702 is configured to storean instruction. The processor 1701 is configured to: execute theinstruction stored in the memory 1702, control the receiver 1703 toreceive information, and control the transmitter 1704 to sendinformation.

The processor 1701 is configured to execute the instruction stored inthe memory 1702, the processor 1701 may be configured to perform acorresponding operation and/or function of the processing module 720 inthe network device 700, and the receiver 1703 and the transmitter 1704may be configured to perform a corresponding operation and/or functionof the transceiver module 710 in the network device 700. For brevity,details are not described herein again.

FIG. 22 is a schematic structural diagram of a network device 1800according to an embodiment of this application. As shown in FIG. 22 ,the network device 1800 includes a processor 1801, a memory 1802, areceiver 1803, and a transmitter 1804. These components communicate withand are connected to each other. The memory 1802 is configured to storean instruction. The processor 1801 is configured to: execute theinstruction stored in the memory 1802, control the receiver 1803 toreceive information, and control the transmitter 1804 to sendinformation.

The processor 1801 is configured to execute the instruction stored inthe memory 1802, the processor 1801 may be configured to perform acorresponding operation and/or function of the processing module 820 inthe network device 800, and the receiver 1803 and the transmitter 1804may be configured to perform a corresponding operation and/or functionof the transceiver module 810 in the network device 800. For brevity,details are not described herein again.

FIG. 23 is a schematic structural diagram of a network device 1900according to an embodiment of this application. As shown in FIG. 23 ,the network device 1900 includes a processor 1901, a memory 1902, areceiver 1903, and a transmitter 1904. These components communicate withand are connected to each other. The memory 1902 is configured to storean instruction. The processor 1901 is configured to: execute theinstruction stored in the memory 1902, control the receiver 1903 toreceive information, and control the transmitter 1904 to sendinformation.

The processor 1901 is configured to execute the instruction stored inthe memory 1902, the processor 1901 may be configured to perform acorresponding operation and/or function of the processing module 910 inthe network device 900, and the receiver 1903 and the transmitter 1904may be configured to perform a corresponding operation and/or functionof the transceiver module 920 in the network device 900. For brevity,details are not described herein again.

FIG. 24 is a schematic structural diagram of a terminal device 2000according to an embodiment of this application. As shown in FIG. 24 ,the terminal device 2000 includes a processor 2001, a memory 2002, areceiver 2003, and a transmitter 2004. These components communicate withand are connected to each other. The memory 2002 is configured to storean instruction. The processor 2001 is configured to: execute theinstruction stored in the memory 2002, control the receiver 2003 toreceive information, and control the transmitter 2004 to sendinformation.

The processor 2001 is configured to execute the instruction stored inthe memory 2002, the processor 2001 may be configured to perform acorresponding operation and/or function of the processing module 1020 inthe terminal device 1000, and the receiver 2003 and the transmitter 2004may be configured to perform a corresponding operation and/or functionof the transceiver module 1010 in the terminal device 1000. For brevity,details are not described herein again.

FIG. 25 is a schematic structural diagram of a terminal device 2100according to an embodiment of this application. As shown in FIG. 25 ,the terminal device 2100 includes a processor 2101, a memory 2102, areceiver 2103, and a transmitter 2104. These components communicate withand are connected to each other. The memory 2102 is configured to storean instruction. The processor 2101 is configured to: execute theinstruction stored in the memory 2102, control the receiver 2103 toreceive information, and control the transmitter 2104 to sendinformation.

The processor 2101 is configured to execute the instruction stored inexecute the memory 2102, the processor 2101 may be configured to performa corresponding operation and/or function of the processing module 1120in the terminal device 1100, and the receiver 2103 and the transmitter2104 may be configured to perform a corresponding operation and/orfunction of the transceiver module 1110 in the terminal device 1100. Forbrevity, details are not described herein again.

FIG. 26 is a schematic structural diagram of a terminal device 2200according to an embodiment of this application. As shown in FIG. 26 ,the terminal device 2200 includes a processor 2201, a memory 2202, areceiver 2203, and a transmitter 2204. These components communicate withand are connected to each other. The memory 2202 is configured to storean instruction. The processor 2201 is configured to: execute theinstruction stored in the memory 2202, control the receiver 2203 toreceive information, and control the transmitter 2204 to sendinformation.

The processor 2201 is configured to execute the instruction stored inthe memory 2202, the processor 2201 may be configured to perform acorresponding operation and/or function of the processing module 1210 inthe terminal device 1200, and the receiver 2203 and the transmitter 2204may be configured to perform a corresponding operation and/or functionof the transceiver module 1220 in the terminal device 1200. For brevity,details are not described herein again.

FIG. 27 is a schematic structural diagram of a network device 2300according to an embodiment of this application. As shown in FIG. 27 ,the network device 2300 includes a processor 2301, a memory 2302, areceiver 2303, and a transmitter 2304. These components communicate withand are connected to each other. The memory 2302 is configured to storean instruction. The processor 2301 is configured to: execute theinstruction stored in the memory 2302, control the receiver 2303 toreceive information, and control the transmitter 2304 to sendinformation.

The processor 2301 is configured to execute the instruction stored inthe memory 2302, the processor 2301 may be configured to perform acorresponding operation and/or function of the processing module 1310 inthe network device 1300, and the receiver 2303 and the transmitter 2304may be configured to perform a corresponding operation and/or functionof the transceiver module 1320 in the network device 1300. For brevity,details are not described herein again.

An embodiment of this application further provides a system chip. Thesystem chip includes an input/output interface, at least one processor,at least one memory, and a bus, where the at least one memory isconfigured to store an instruction, and the at least one processor isconfigured to invoke the instruction in the at least one memory, toperform operations in the methods according to the foregoing aspects.

In the embodiments of this application, it should be noted that theforegoing method embodiments in the embodiments of this application maybe applied to a processor, or may be implemented by a processor. Theprocessor may be an integrated circuit chip and has a signal processingcapability. In an implementation process, the steps in the foregoingmethod embodiments may be implemented by using a hardware integratedlogic circuit in the processor, or by using instructions in a form ofsoftware. The foregoing processor may be a general purpose processor, adigital signal processor (Digital Signal Processor, DSP), anapplication-specific integrated circuit (Application Specific IntegratedCircuit, ASIC), a field programmable gate array (Field Programmable GateArray, FPGA) or another programmable logic device, a discrete gate or atransistor logic device, or a discrete hardware component. It mayimplement or perform the methods, the steps, and logical block diagramsthat are disclosed in the embodiments of this application. The generalpurpose processor may be a microprocessor or the processor may be anyconventional processor, or the like. Steps of the methods disclosed inthe embodiments of this application may be directly performed andcompleted by a hardware decoding processor, or may be performed andcompleted by using a combination of hardware and software modules in thedecoding processor. The software module may be located in a maturestorage medium in the art, such as a random access memory, a flashmemory, a read-only memory, a programmable read-only memory or anelectrically erasable programmable memory, or a register. The storagemedium is located in the memory, and the processor reads information inthe memory and completes the steps in the foregoing methods incombination with hardware of the processor.

It may be understood that the memory in the embodiments of thisapplication may be a volatile memory or a non-volatile memory, or mayinclude a volatile memory and a non-volatile memory. The non-volatilememory may be a read-only memory (Read-Only Memory, ROM), a programmableread-only memory (Programmable ROM, PROM), an erasable programmableread-only memory (Erasable PROM, EPROM), an electrically erasableprogrammable read-only memory (Electrically EPROM, EEPROM), or a flashmemory. The volatile memory may be a random access memory (Random AccessMemory, RAM), used as an external cache. Through example but notlimitative description, many forms of RAMs may be used, for example, astatic random access memory (Static RAM, SRAM), a dynamic random accessmemory (Dynamic RAM, DRAM), a synchronous dynamic random access memory(Synchronous DRAM, SDRAM), a double data rate synchronous dynamic randomaccess memory (Double Data Rate SDRAM, DDR SDRAM), an enhancedsynchronous dynamic random access memory (Enhanced SDRAM, ESDRAM), asynchronous link dynamic random access memory (Synchlink DRAM, SLDRAM),and a direct rambus dynamic random access memory (Direct Rambus RAM, DRRAM). It should be noted that the memory in the system and the methoddescribed in this specification intends to include, but is not limitedto, these memories and any other appropriate types of memories.

It should be understood that “one embodiment” or “an embodiment”mentioned in the entire specification mean that particular features,structures, or characteristics related to the embodiment are included inat least one embodiment of this application. Therefore, “in oneembodiment” or “in an embodiment” appearing throughout thisspecification may be not necessarily a same embodiment. Moreover, theparticular features, structure or characteristics may be combined in oneor more embodiments in any proper manner. It should be understood thatsequence numbers of the foregoing processes do not mean executionsequences in various embodiments of this application. The executionsequences of the processes should be determined based on functions andinternal logic of the processes, and should not be construed as anylimitation on the implementation processes of the embodiments of thisapplication.

In addition, the terms “system” and “network” may be usedinterchangeably in this specification. The term “and/or” in thisspecification describes only an association relationship for describingassociated objects and represents that three relationships may exist.For example, A and/or B may represent the following three cases: Only Aexists, both A and B exist, and only B exists. In addition, thecharacter “/” in this specification generally indicates an “or”relationship between the associated objects.

It should be understood that in the embodiments of this application, “Bcorresponding to A” indicates that B is associated with A, and B may bedetermined according to A. However, it should be further understood thatdetermining A based on B does not mean that B is determined based on Aonly; that is, B may also be determined based on A and/or otherinformation.

All or some of the foregoing embodiments may be implemented by usingsoftware, hardware, firmware, or any combination thereof. When softwareis used to implement the embodiments, the embodiments may be implementedcompletely or partially in a form of a computer program product. Thecomputer program product may include one or more computer instructions.When the computer program instructions are loaded and executed on thecomputer, the procedure or functions according to the embodiments ofthis application are all or partially generated. The computer may be ageneral purpose computer, a dedicated computer, a computer network, oranother programmable apparatus. The computer instructions may be storedin a computer-readable storage medium or may be transmitted from acomputer-readable storage medium to another computer-readable storagemedium. For example, the computer instructions may be transmitted from awebsite, computer, server, or data center to another website, computer,server, or data center in a wired (for example, a coaxial cable, anoptical fiber, or a digital subscriber line (DSL)) or wireless (forexample, infrared, radio, or microwave) manner. The computer-readablestorage medium may be any usable medium accessible by a computer, or adata storage device, such as a server or a data center, integrating oneor more usable media. The usable medium may be a magnetic medium (forexample, a soft disk, a hard disk, or a magnetic disk), an opticalmedium (for example, a DVD), a semiconductor medium (for example, asolid state disk Solid State Disk (SSD)), or the like.

A person of ordinary skill in the art may be aware that, the units andalgorithm steps in the examples described with reference to theembodiments disclosed in this specification may be implemented byelectronic hardware or a combination of computer software and electronichardware. Whether the functions are performed by hardware or softwaredepends on particular applications and design constraint conditions ofthe technical solutions. A person skilled in the art may use differentmethods to implement the described functions for each particularapplication, but it should not be considered that the implementationgoes beyond the scope of this application.

It may be clearly understood by a person skilled in the art that, forthe purpose of convenient and brief description, for a detailed workingprocess of the system, the apparatus, and the unit, refer to acorresponding process in the method embodiments. Details are notdescribed herein again.

In the several embodiments provided in this application, it should beunderstood that the disclosed system, apparatus, and method may beimplemented in other manners. For example, the described apparatusembodiment is merely an example. For example, the unit division ismerely logical function division and may be other division during actualimplementation. For example, a plurality of units or components may becombined or integrated into another system, or some features may beignored or not performed. In addition, the displayed or discussed mutualcouplings or direct couplings or communication connections may beimplemented by using some interfaces. The indirect couplings orcommunication connections between the apparatuses or units may beimplemented in electronic, mechanical, or other forms.

The units described as separate parts may or may not be physicallyseparate, and parts displayed as units may or may not be physical units,may be located in one position, or may be distributed on a plurality ofnetwork units. Some or all of the units may be selected based on actualrequirements to achieve the objectives of the solutions of theembodiments.

In addition, functional units in the embodiments of this application maybe integrated into one processing unit, or each of the units may existalone physically, or two or more units are integrated into one unit.

When the functions are implemented in a form of a software functionalunit and sold or used as an independent product, the functions may bestored in a computer-readable storage medium. Based on such anunderstanding, the technical solutions of this application essentially,or the part contributing to the prior art, or some of the technicalsolutions may be implemented in a form of a software product. Thecomputer software product is stored in a storage medium, and includesseveral instructions for instructing a computer device (which may be apersonal computer, a server, a network device, or the like) to performall or some of the steps of the methods described in the embodiments ofthis application. The foregoing storage medium includes: any medium thatcan store program code, such as a USB flash drive, a removable harddisk, a read-only memory, a random access memory, a magnetic disk, or anoptical disc.

The foregoing descriptions are merely specific implementations of thisapplication, but are not intended to limit the protection scope of thisapplication. Any variation or replacement readily figured out by aperson skilled in the art within the technical scope disclosed in thisapplication shall fall within the protection scope of this application.Therefore, the protection scope of this application shall be subject tothe protection scope of the claims.

What is claimed is:
 1. A data transmission method, comprising:receiving, by a first network node, a first report from a terminaldevice, wherein the first report indicates an uplink data volume of abuffer of the terminal device, and the first network node is a data unit(DU) of a base station; determining, by the first network node, based onthe uplink data volume of the buffer of the terminal device, a need toswitch the terminal device to an active state or perform offloadingconfiguration of a radio bearer for the terminal device; andtransmitting, by the first network node, first indication information toa second network node, wherein the second network node is a central unit(CU) of the base station, and wherein the first indication informationcomprises information about the uplink data volume of the buffer of theterminal device, or the first indication information indicates arelationship between the uplink data volume of the buffer of theterminal device and a predefined data volume threshold, and the firstindication information instructs the second network node to switch theterminal device to the active state or perform offloading configurationof the radio bearer for the terminal device.
 2. The method according toclaim 1, wherein the method further comprises: receiving, by the firstnetwork node, second indication information from the second networknode, wherein the second indication information indicates the predefineddata volume threshold, or the second indication information instructsthe first network node to send information about the uplink data volumeof the buffer of the terminal device to the second network node.
 3. Themethod according to claim 1, wherein the method further comprises:receiving, by the first network node from the terminal device, a reportindicating the uplink data volume of the buffer of the terminal device.4. The method according to claim 1, wherein: the first network nodecomprises one or more of: a function of a radio link control protocollayer, a function of a media access control layer, or a function of aphysical layer.
 5. A first network node, comprising: at least oneprocessor; and one or more memories coupled to the at least oneprocessor and storing programming instructions for execution by the atleast one processor, the programming instructions instruct the at leastone processor to perform operations comprising: receiving a first reportfrom a terminal device, wherein the first report indicates an uplinkdata volume of a buffer of the terminal device, and the first networknode is a data unit (DU) of a base station; determining, based on theuplink data volume of the buffer of the terminal device, a need toswitch the terminal device to an active state or perform offloadingconfiguration of a radio bearer for the terminal device; andtransmitting, first indication information to a second network node,wherein the second network node is a central unit (CU) of the basestation, and wherein the first indication information comprisesinformation about the uplink data volume of the buffer of the terminaldevice, or the first indication information indicates a relationshipbetween the uplink data volume of the buffer of the terminal device anda predefined data volume threshold, and the first indication informationinstructs the second network node to switch the terminal device to theactive state or perform offloading configuration of the radio bearer forthe terminal device.
 6. The first network node according to claim 5,wherein the operations further comprise: receiving, second indicationinformation from the second network node, wherein the second indicationinformation indicates the predefined data volume threshold, or thesecond indication information instructs the first network node to sendinformation about the uplink data volume of the buffer of the terminaldevice to the second network node.
 7. The first network node accordingto claim 5, wherein the operations further comprise: receiving, from theterminal device a report indicating the uplink data volume of the bufferof the terminal device.
 8. The first network node according to claim 5,wherein: the first network node comprises one or more of: a function ofa radio link control protocol layer, a function of a media accesscontrol layer, or a function of a physical layer.
 9. The methodaccording to claim 1, wherein: the second network node comprises one ormore of: a function of a packet data convergence protocol layer, afunction of a service data adaptation layer, or a radio resource controlfunction.
 10. The first network node according to claim 5, wherein: thesecond network node comprises one or more of: a function of a packetdata convergence protocol layer, a function of a service data adaptationlayer, or a radio resource control function.
 11. A non-transitory,computer-readable medium storing one or more instructions executable bya first network node to perform operations comprising: receiving, by afirst network node, a first report from a terminal device, wherein thefirst report indicates an uplink data volume of a buffer of the terminaldevice, and the first network node is a data unit (DU) of a basestation; determining, by the first network node, based on the uplinkdata volume of the buffer of the terminal device, a need to switch theterminal device to an active state or perform offloading configurationof a radio bearer for the terminal device; and transmitting, by thefirst network node, first indication information to a second networknode, wherein the second network node is a central unit (CU) of the basestation, and wherein the first indication information comprisesinformation about the uplink data volume of the buffer of the terminaldevice, or the first indication information indicates a relationshipbetween the uplink data volume of the buffer of the terminal device anda predefined data volume threshold, and the first indication informationinstructs the second network node to switch the terminal device to theactive state or perform offloading configuration of the radio bearer forthe terminal device.
 12. The non-transitory, computer-readable mediumaccording to claim 11, wherein the operations further comprise:receiving, second indication information from the second network node,wherein the second indication information indicates the predefined datavolume threshold, or the second indication information instructs thefirst network node to send information about the uplink data volume ofthe buffer of the terminal device to the second network node.
 13. Thenon-transitory, computer-readable medium according to claim 11, whereinthe operations further comprise: receiving, from the terminal device areport indicating the uplink data volume of the buffer of the terminaldevice.
 14. The non-transitory, computer-readable medium according toclaim 11, wherein: the first network node comprises one or more of: afunction of a radio link control protocol layer, a function of a mediaaccess control layer, or a function of a physical layer.
 15. Thenon-transitory, computer-readable medium according to claim 11, wherein:the second network node comprises one or more of: a function of a packetdata convergence protocol layer, a function of a service data adaptationlayer, or a radio resource control function.